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Panwaria P, Das A. N···C═O n → π* Interaction: Gas-Phase Electronic and Vibrational Spectroscopy Combined with Quantum Chemistry Calculations. J Phys Chem A 2024; 128:4685-4693. [PMID: 38814588 DOI: 10.1021/acs.jpca.4c02181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2024]
Abstract
Herein, we have used gas-phase electronic and vibrational spectroscopic techniques for the first time to study the N···C═O n → π* interaction in ethyl 2-(2-(dimethylamino) phenyl) acetate (NMe2-Ph-EA). We have measured the electronic spectra of NMe2-Ph-EA in the mass channels of its two distinct fragments of m/z = 15 and 192 using a resonant two-photon ionization technique as there was extensive photofragmentation of NMe2-Ph-EA. Identical electronic spectra obtained in the mass channels of both fragments confirm the dissociation of NMe2-Ph-EA in the ionic state, and hence, the electronic spectrum of the fragment represents that of NMe2-Ph-EA only. UV-UV hole-burning spectroscopy proved the presence of a single conformer of NMe2-Ph-EA in the experiment. Detailed quantum chemistry calculations reveal the existence of a N···C═O n → π* interaction in all six low-energy conformers of NMe2-Ph-EA. A comparison of the IR spectrum of NMe2-Ph-EA acquired from the gas-phase experiment with those obtained from theoretical calculations indicates that the experimentally observed conformer has a N···C═O n → π* interaction. The present finding might be further valuable in drug design and their recognition based on the N···C═O n → π* interaction.
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Affiliation(s)
- Prakash Panwaria
- Department of Chemistry, Indian Institute of Science Education and Research Pune, Dr. Homi Bhabha Road, Pashan, Pune 411008, India
| | - Aloke Das
- Department of Chemistry, Indian Institute of Science Education and Research Pune, Dr. Homi Bhabha Road, Pashan, Pune 411008, India
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2
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Yin C, Ye H, Hai Y, Zou H, You L. Aromatic-Carbonyl Interactions as an Emerging Type of Non-Covalent Interactions. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2310337. [PMID: 38561959 PMCID: PMC11165483 DOI: 10.1002/advs.202310337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2023] [Revised: 02/23/2024] [Indexed: 04/04/2024]
Abstract
Aromatic-carbonyl (Ar···C═O) interactions, attractive interactions between the arene plane and the carbon atom of carbonyl, are in the infancy as one type of new supramolecular bonding forces. Here the study and functionalization of aromatic-carbonyl interactions in solution is reported. A combination of aromatic-carbonyl interactions and dynamic covalent chemistry provided a versatile avenue. The stabilizing role and mechanism of arene-aldehyde/imine interactions are elucidated through crystal structures, NMR studies, and computational evidence. The movement of imine exchange equilibria further allowed the quantification of the interplay between arene-aldehyde/imine interactions and dynamic imine chemistry, with solvent effects offering another handle and matching the electrostatic feature of the interactions. Moreover, arene-aldehyde/imine interactions enabled the reversal of kinetic and thermodynamic selectivity and sorting of dynamic covalent libraries. To show the functional utility diverse modulation of fluorescence signals is realized with arene-aldehyde/imine interactions. The results should find applications in many aspects, including molecular recognition, assemblies, catalysis, and intelligent materials.
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Affiliation(s)
- Chaowei Yin
- State Key Laboratory of Structural ChemistryFujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhouFujian350002China
- University of Chinese Academy of SciencesChinese Academy of SciencesBeijing100049China
| | - Hebo Ye
- State Key Laboratory of Structural ChemistryFujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhouFujian350002China
| | - Yu Hai
- State Key Laboratory of Structural ChemistryFujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhouFujian350002China
| | - Hanxun Zou
- State Key Laboratory of Structural ChemistryFujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhouFujian350002China
| | - Lei You
- State Key Laboratory of Structural ChemistryFujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhouFujian350002China
- University of Chinese Academy of SciencesChinese Academy of SciencesBeijing100049China
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3
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Falcioni F, Bennett S, Stroer-Jarvis P, Popelier PLA. Probing Non-Covalent Interactions through Molecular Balances: A REG-IQA Study. Molecules 2024; 29:1043. [PMID: 38474554 DOI: 10.3390/molecules29051043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 02/19/2024] [Accepted: 02/21/2024] [Indexed: 03/14/2024] Open
Abstract
The interaction energies of two series of molecular balances (1-X with X = H, Me, OMe, NMe2 and 2-Y with Y = H, CN, NO2, OMe, NMe2) designed to probe carbonyl…carbonyl interactions were analysed at the B3LYP/6-311++G(d,p)-D3 level of theory using the energy partitioning method of Interacting Quantum Atoms/Fragments (IQA/IQF). The partitioned energies are analysed by the Relative Energy Gradient (REG) method, which calculates the correlation between these energies and the total energy of a system, thereby explaining the role atoms have in the energetic behaviour of the total system. The traditional "back-of-the-envelope" open and closed conformations of molecular balances do not correspond to those of the lowest energy. Hence, more care needs to be taken when considering which geometries to use for comparison with the experiment. The REG-IQA method shows that the 1-H and 1-OMe balances behave differently to the 1-Me and 1-NMe2 balances because the latter show more prominent electrostatics between carbonyl groups and undergoes a larger dihedral rotation due to the bulkiness of the functional groups. For the 2-Y balance, REG-IQA shows the same behaviour across the series as the 1-H and 1-OMe balances. From an atomistic point of view, the formation of the closed conformer is favoured by polarisation and charge-transfer effects on the amide bond across all balances and is counterbalanced by a de-pyramidalisation of the amide nitrogen. Moreover, focusing on the oxygen of the amide carbonyl and the α-carbon of the remaining carbonyl group, electrostatics have a major role in the formation of the closed conformer, which goes against the well-known n-π* interaction orbital overlap concept. However, REG-IQF shows that exchange-correlation energies overtake electrostatics for all the 2-Y balances when working with fragments around the carbonyl groups, while they act on par with electrostatics for the 1-OMe and 1-NMe2. REG-IQF also shows that exchange-correlation energies in the 2-Y balance are correlated to the inductive electron-donating and -withdrawing trends on aromatic groups. We demonstrate that methods such as REG-IQA/IQF can help with the fine-tuning of molecular balances prior to the experiment and that the energies that govern the probed interactions are highly dependent on the atoms and functional groups involved.
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Affiliation(s)
- Fabio Falcioni
- Department of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Sophie Bennett
- Department of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Pallas Stroer-Jarvis
- Department of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Paul L A Popelier
- Department of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, UK
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Peng PK, Isho A, May JA. Regio- and enantioselective synthesis of acyclic quaternary carbons via organocatalytic addition of organoborates to (Z)-Enediketones. Nat Commun 2024; 15:504. [PMID: 38218961 PMCID: PMC10787796 DOI: 10.1038/s41467-024-44744-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Accepted: 01/03/2024] [Indexed: 01/15/2024] Open
Abstract
The chemical synthesis of molecules with closely packed atoms having their bond coordination saturated is a challenge to synthetic chemists, especially when three-dimensional control is required. The organocatalyzed asymmetric synthesis of acyclic alkenylated, alkynylated and heteroarylated quaternary carbon stereocenters via 1,4-conjugate addition is here catalyzed by 3,3´-bisperfluorotoluyl-BINOL. The highly useful products (31 examples) are produced in up to 99% yield and 97:3 er using enediketone substrates and potassium trifluoroorganoborate nucleophiles. In addition, mechanistic experiments show that the (Z)-isomer is the reactive form, ketone rotation at the site of bond formation is needed for enantioselectivity, and quaternary carbon formation is favored over tertiary. Density functional theory-based calculations show that reactivity and selectivity depend on a key n→π* donation by the unbound ketone's oxygen lone pair to the boronate-coordinated ketone in a 5-exo-trig cyclic ouroboros transition state. Transformations of the conjugate addition products to key quaternary carbon-bearing synthetic building blocks proceed in good yield.
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Affiliation(s)
- Po-Kai Peng
- Department of Chemistry, University of Houston, 3585 Cullen Blvd., Fleming Building Rm 112, Houston, TX, 77204-5003, USA
| | - Andrew Isho
- Department of Chemistry, University of Houston, 3585 Cullen Blvd., Fleming Building Rm 112, Houston, TX, 77204-5003, USA
| | - Jeremy A May
- Department of Chemistry, University of Houston, 3585 Cullen Blvd., Fleming Building Rm 112, Houston, TX, 77204-5003, USA.
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5
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Gravillier LA, Cockroft SL. Context-Dependent Significance of London Dispersion. Acc Chem Res 2023; 56:3535-3544. [PMID: 37994023 DOI: 10.1021/acs.accounts.3c00625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2023]
Abstract
ConspectusLondon forces constitute an attractive component of van der Waals interactions and originate from transient correlated momentary dipoles in adjacent atoms. The in-depth investigation of London dispersion forces poses notable challenges, especially in solution, owing to their inherently weak and competing character. Our objective in this Account is to shed light on the context-dependent significance of London dispersion forces by contrasting our own experimental findings with those from other research endeavors. Specifically, we will explore how factors such as the choice of system and solvent can influence the apparent role of London dispersion forces in molecular recognition processes. We initiate our Account by scrutinizing the Wilcox balance, which has yielded diverse and occasionally contradictory results. Following that, we provide an overview of the role of London dispersion forces and their context-dependent variations, encompassing alkyl-alkyl, halogen-π, alkyl-π, and aromatic stacking interactions.Several experimental investigations have revealed how difficult it is to measure the significance of London dispersion in solution. Indeed, dispersion forces seldom act as the exclusive driving force in molecular recognition processes, and solvation energetics also strongly influence equilibria and kinetics. Molecular balances that bring apolar functional groups into contact have proven to be instrumental in the experimental measurement of dispersion. The intramolecular approach avoids the need to pay the entropic cost of bringing interacting groups into contact, while also enabling solvent screening. Such experimental studies have found dispersion interactions between functional groups to be very weak (<5 kJ mol-1), meaning that they frequently take backstage to electrostatic contributions and solvophobic effects and are readily damped by competitive dispersion interactions with the solvent. By using such approaches, competitive dispersion interactions with the solvent have been shown to be described by the bulk polarizability of the solvent (perfluoroalkanes have the lowest bulk polarizabilities, while carbon disulfide has one of the highest). Dispersion interactions are also strongly distance-dependent, which results in considerable context-dependent outcomes across different investigations. For example, we caution against the risk of attributing the stability of a "more sterically hindered" isomer as arising from intramolecular dispersion forces. The total energy of the system can reveal other contributions to stability, such as nonintuitive minimization of strain elsewhere in the molecule. Indeed, the delicate distance-dependent balance between sterics and London dispersion means that even subtle changes in size and geometry can lead to disparate behavior. Similarly, solvophobic effects also contribute to stabilizing contacts between bulky functional groups, which can be revealed if there is a correlation with the cohesive energy density of the solvent.
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Affiliation(s)
- Louis-Albin Gravillier
- EaStCHEM School of Chemistry, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh EH9 3FJ, U.K
| | - Scott L Cockroft
- EaStCHEM School of Chemistry, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh EH9 3FJ, U.K
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You L. Dual reactivity based dynamic covalent chemistry: mechanisms and applications. Chem Commun (Camb) 2023; 59:12943-12958. [PMID: 37772969 DOI: 10.1039/d3cc04022d] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/30/2023]
Abstract
Dynamic covalent chemistry (DCC) focuses on the reversible formation, breakage, and exchange of covalent bonds and assemblies, setting a bridge between irreversible organic synthesis and supramolecular chemistry and finding wide utility. In order to enhance structural and functional diversity and complexity, different types of dynamic covalent reactions (DCRs) are placed in one vessel, encompassing orthogonal DCC without crosstalk and communicating DCC with a shared reactive functional group. As a means of adding tautomers, widespread in chemistry, to interconnected DCRs and combining the features of orthogonal and communicating DCRs, a concept of dual reactivity based DCC and underlying structural and mechanistic insights are summarized. The manipulation of the distinct reactivity of structurally diverse ring-chain tautomers allows selective activation and switching of reaction pathways and corresponding DCRs (C-N, C-O, and C-S) and assemblies. The coupling with photoswitches further enables light-mediated formation and scission of multiple types of reversible covalent bonds. To showcase the capability of dual reactivity based DCC, the versatile applications in dynamic polymers and luminescent materials are presented, paving the way for future functionalization studies.
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Affiliation(s)
- Lei You
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China.
- University of Chinese Academy of Sciences, Beijing 100049, China
- Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou 350108, China
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7
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Wang XD, Zhu J, Wang DX. Intermolecular n→π* Interactions in Supramolecular Chemistry and Catalysis. Chempluschem 2023; 88:e202300288. [PMID: 37609956 DOI: 10.1002/cplu.202300288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 08/19/2023] [Accepted: 08/21/2023] [Indexed: 08/24/2023]
Abstract
The n→π* interactions describing attractive force between lone pairs (lps) of nucleophile and carbonyl or polarized unsaturated bonds have recently attracted growing attentions in various disciplines. So far, such non-covalent driving force are mainly concentrated to intramolecular systems. Intermolecular n→π* interactions in principle could produce fascinated supramolecular systems or facilitate organic reactions, however, they remain largely underexplored due to the very weak energy of individual interaction. This review attempts to give an overview of the challenging intermolecular n→π* interactions, much efforts emphasize the supramolecular systems, catalytic processes and spectroscopic measurements.
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Affiliation(s)
- Xu-Dong Wang
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Jun Zhu
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - De-Xian Wang
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
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8
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Abstract
While a good deal of information has accumulated concerning the manner in which an intramolecular noncovalent bond can affect the relative energies of various conformers, less is known about how such bonds might affect the dynamics of interconversion between them. A series of molecules are constructed in which symmetrically equivalent conformers containing a noncovalent bond can be interconverted by a bond rotation, the energy barrier to which is computed by quantum chemical methods. The rotation of a CF3 group attached to a phenyl ring is speeded up if a Se··F chalcogen bond can be formed with a SeH or SeF group placed in an ortho position, a bond that is present in and stabilizes the rotational transition state. The analogous SnF3 group can, on the other hand, engage in a Sn··Se tetrel bond in its global minimum. The energetic cost of breakage of this bond is not fully compensated by the appearance of a Se··F chalcogen bond in the rotational transition state. Other systems were designed by placing two phenyl rings on opposite ends of an octahedrally disposed SeF4 group. A high barrier inhibits their rotation with bulky Br atoms in ortho positions, but this barrier is lowered if Br is replaced by groups that can engage in either chalcogen (SeH or SeF) or pnicogen (AsH2) bonds with the F atoms in the rotational transition state. The barrier reduction is closely related to the strength of these noncovalent bonds.
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Affiliation(s)
- Steve Scheiner
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322-0300, United States
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9
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Liu M, Han X, Chen H, Peng Q, Huang H. A molecular descriptor of intramolecular noncovalent interaction for regulating optoelectronic properties of organic semiconductors. Nat Commun 2023; 14:2500. [PMID: 37127693 PMCID: PMC10151346 DOI: 10.1038/s41467-023-38078-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Accepted: 04/11/2023] [Indexed: 05/03/2023] Open
Abstract
In recent years, intramolecular noncovalent interaction has become an important means to modulate the optoelectronic performances of organic/polymeric semiconductors. However, it lacks a deep understanding and a direct quantitative relationship among the molecular geometric structure, strength of noncovalent interaction, and optoelectronic properties in organic/polymeric semiconductors. Herein, upon systematical theoretical calculations on 56 molecules with and without noncovalent interactions (X···Y, X = O, S, Se, Te; Y = C, F, O, S, Cl), we reveal the essence of the interactions and the dependence of its strength on the molecular geometry. Importantly, a descriptor S is established as a function of several basic geometric parameters to well characterize the noncovalent interaction energy, which exhibits a good inverse correlation with the reorganization energies of the photo-excited states or electron-pumped charged states in organic/polymeric semiconductors. In particular, the experimental 1H, 77Se, and 125Te NMR, the optical absorption and emission spectra, and single crystal structures of eight compounds fully confirm the theoretical predictions. This work provides a simple descriptor to characterize the strength of noncovalent intramolecular interactions, which is significant for molecular design and property prediction.
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Affiliation(s)
- Meihui Liu
- School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Xiao Han
- College of Materials Science and Opto-Electronic Technology & CAS Center for Excellence in Topological Quantum Computation & Key Laboratory of Vacuum Physics, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Hao Chen
- College of Materials Science and Opto-Electronic Technology & CAS Center for Excellence in Topological Quantum Computation & Key Laboratory of Vacuum Physics, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Qian Peng
- School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China.
| | - Hui Huang
- College of Materials Science and Opto-Electronic Technology & CAS Center for Excellence in Topological Quantum Computation & Key Laboratory of Vacuum Physics, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China.
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10
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Feng J, Zhang G, Wen J, He X, Li M. Ultra-Thin 2D Ionic Salt Supported with Strong Hydrogen-Bonding Assisted Ionic Interaction. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2207509. [PMID: 36799141 DOI: 10.1002/smll.202207509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 01/26/2023] [Indexed: 05/11/2023]
Abstract
2D materials have attracted great interest since the report of graphene. However, because of the fragile stability of ultra-thin nanosheets, most studies are restricted to sheets maintained by strong covalent or coordination bonds. The research on which kind of bonds can maintain the free-standing existence of 2D nanosheets is still of great significance. Recently, 2D ionic salts are successfully synthesized on substrates, but whether 2D ionic salts can free-stand is still a problem. Herein this problem is addressed by a free-standing 2D ionic salt (thickness: ≈2 nm) exfoliated from a 4,4'-bipyridinium hydrochloride salt crystal. The stability of this 2D salt is supported by a strong NH···Cl hydrogen (H)-bonding assisted ionic interaction (17.99 kcal mol-1 ), which is verified by density functional theory calculation and natural bond orbital analysis. The salt crystal has strong air-stable radicals inside and the 2D ionic salt exhibits red fluorescence in solution and in solid-state, especially in solution the stokes shifts are very large (≈ 386 nm). This breakthrough work is not only beneficial for the construction of novel 2D materials but also for the understanding of H-bonding interactions.
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Affiliation(s)
- Jiaxin Feng
- Collaborative Innovation Center for Advanced Organic Chemical Materials Co-constructed by the Province and Ministry, Ministry-of-Education Key Laboratory for the Synthesis and Application of Organic Functional Molecules, Hubei Key Laboratory of Polymer Materials, College of Chemistry and Chemical Engineering, Hubei University, Wuhan, 430062, P. R. China
| | - Ganbing Zhang
- Collaborative Innovation Center for Advanced Organic Chemical Materials Co-constructed by the Province and Ministry, Ministry-of-Education Key Laboratory for the Synthesis and Application of Organic Functional Molecules, Hubei Key Laboratory of Polymer Materials, College of Chemistry and Chemical Engineering, Hubei University, Wuhan, 430062, P. R. China
| | - Ju Wen
- Collaborative Innovation Center for Advanced Organic Chemical Materials Co-constructed by the Province and Ministry, Ministry-of-Education Key Laboratory for the Synthesis and Application of Organic Functional Molecules, Hubei Key Laboratory of Polymer Materials, College of Chemistry and Chemical Engineering, Hubei University, Wuhan, 430062, P. R. China
| | - Xianying He
- Collaborative Innovation Center for Advanced Organic Chemical Materials Co-constructed by the Province and Ministry, Ministry-of-Education Key Laboratory for the Synthesis and Application of Organic Functional Molecules, Hubei Key Laboratory of Polymer Materials, College of Chemistry and Chemical Engineering, Hubei University, Wuhan, 430062, P. R. China
| | - Ming Li
- Collaborative Innovation Center for Advanced Organic Chemical Materials Co-constructed by the Province and Ministry, Ministry-of-Education Key Laboratory for the Synthesis and Application of Organic Functional Molecules, Hubei Key Laboratory of Polymer Materials, College of Chemistry and Chemical Engineering, Hubei University, Wuhan, 430062, P. R. China
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11
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Yin C, Lu H, Ye H, Feng Z, Zou H, Zhang M, You L. Double n→π* Interactions with One Electron Donor: Structural and Mechanistic Insights. Org Lett 2023; 25:1470-1475. [PMID: 36856609 DOI: 10.1021/acs.orglett.3c00205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2023]
Abstract
Double n→π* interactions between one common electron donor of the carbonyl oxygen and two individual acceptor aldehyde/imine units are presented. The structural and mechanistic insights were revealed through a collection of experimental and computational evidence. The orientation and further energetic dependence of orbital interactions were facilely regulated by the size of cyclic urea scaffolds, the bulkiness of aldehydes/imines, and the flexibility of imine macrocycles.
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Affiliation(s)
- Chaowei Yin
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hanwei Lu
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hebo Ye
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China
| | - Zelin Feng
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China
| | - Hanxun Zou
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China
| | - Meilan Zhang
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China
| | - Lei You
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China.,University of Chinese Academy of Sciences, Beijing 100049, China
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12
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Zhu J, Wang XD, Ao YF, Wang QQ, Wang DX. Intermolecular n→π* Interactions Based on a Tailored Multicarbonyl-Containing Macrocycle. Chemistry 2023; 29:e202203485. [PMID: 36445795 DOI: 10.1002/chem.202203485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 11/24/2022] [Accepted: 11/24/2022] [Indexed: 11/30/2022]
Abstract
Towards unexplored intermolecular n→π* interactions, presented herein are the synthesis, structure, self-assembly and function of a multicarbonyl-containing macrocycle calix[2]arene[2]barbiturate 1. X-ray single crystal diffraction reveals the presence of Cl⋅⋅⋅C=O interactions in CH2 Cl2 ⊂1 host-guest complex and multiple intermolecular C=O⋅⋅⋅C=O interactions between molecules 1 in crystalline state. The intermolecular C=O⋅⋅⋅C=O interactions as attractive driving force led to unprecedented self-assembly of nanotube with diameter around 1.4 nm and inner surface engineered by aromatic rings. SEM and TEM images of the self-assembly of 1 demonstrated temperature-dependent morphologies which allows the observation of spheres at 25 °C and rods at 0 °C, respectively. XRD analysis indicated consistent hexagonal patterns in the self-assembly and single crystal lattice, indicating the nanotubes driven by C=O⋅⋅⋅C=O interactions constitute the basic structural architectures of both aggregates. The nanoscopic tubes (pores) formed in the rodlike single crystal engendering the separation of moving dyes were preliminarily investigated by a single-crystal chromatography and crystal-packed column chromatography.
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Affiliation(s)
- Jun Zhu
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.,University of Chinese Academy of Sciences, Beijing, 100049, P. R. China)
| | - Xu-Dong Wang
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Yu-Fei Ao
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.,University of Chinese Academy of Sciences, Beijing, 100049, P. R. China)
| | - Qi-Qiang Wang
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.,University of Chinese Academy of Sciences, Beijing, 100049, P. R. China)
| | - De-Xian Wang
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.,University of Chinese Academy of Sciences, Beijing, 100049, P. R. China)
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13
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Inami H, Inagaki Y, Setaka W. Design of rotational potential in a phenyltriptycene molecular rotor by exploiting CH/π-interaction between tripticil hydrogen and phenyl. Org Biomol Chem 2022; 20:7092-7098. [PMID: 36039900 DOI: 10.1039/d2ob01179d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The chemistry of artificial molecular rotors has recently attracted considerable attention in the field of molecular machines. Phenyltriptycene could be used as a stepwise molecular rotor because it is composed of a phenyl rotor and a triptycene stator, in which the rotational potential can be designed by introducing substituents. In this study, a novel design of the relative energies among three rotamers of a substituted phenyltriptycene by exploiting the CH/π-interaction between a peri-hydrogen and phenyl was investigated. First, the structures of two different phenyltriptycenes were compared to confirm CH/π-interactions. Second, the effects of the substituents of 1,4,5-trichloro-3',5'-dimethoxyphenyltriptycene on the relative energies were investigated by structural analysis, temperature-dependent nuclear magnetic resonance studies, and density functional theory calculations. The obtained results should facilitate the design of novel molecular switches and/or molecular rotors.
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Affiliation(s)
- Hazuki Inami
- Division of Applied Chemistry, Faculty of Urban Environmental Sciences, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397, Japan.
| | - Yusuke Inagaki
- Division of Applied Chemistry, Faculty of Urban Environmental Sciences, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397, Japan.
| | - Wataru Setaka
- Division of Applied Chemistry, Faculty of Urban Environmental Sciences, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397, Japan.
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14
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Norman NJ, Bao ST, Curts L, Hui T, Zheng SL, Shou T, Zeghibe A, Burdick I, Fuehrer H, Huang A. Highly Selective N-Alkylation of Pyrazoles: Crystal Structure Evidence for Attractive Interactions. J Org Chem 2022; 87:10018-10025. [PMID: 35877958 DOI: 10.1021/acs.joc.2c00980] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Inspired by crystal structures, we designed and achieved a catalyst-free Michael reaction for the preparation of an N1-alkyl pyrazole in a high yield (>90%) with excellent regioselectivity (N1/N2 > 99.9:1). The scope of this protocol has been extended to accomplish the first general regioselective N1-alkylation of 1H-pyrazoles to give di-, tri-, and tetra-substituted pyrazoles in a single step. The resulting pyrazoles bear versatile functional groups such as bromo, ester, nitro, and nitrile, offering opportunities for late-stage functionalization. This efficient methodology will have an impact on drug discovery, as several Food and Drug Administration-approved drugs are pyrazole derivatives. A working hypothesis for the regioselectivity is proposed. X-ray crystal structures of the products that highlight the attractive interactions are discussed. This report provides a rare source for the further elucidation of the attractive interactions because the isomeric ratios and the crystal structures are directly related.
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Affiliation(s)
- Natalie J Norman
- Department of Chemistry, Wellesley College, 106 Central Street, Wellesley, Massachusetts 02481, United States
| | - Si Tong Bao
- Department of Chemistry, Wellesley College, 106 Central Street, Wellesley, Massachusetts 02481, United States
| | - Lynne Curts
- Department of Chemistry, Wellesley College, 106 Central Street, Wellesley, Massachusetts 02481, United States
| | - Tiffani Hui
- Department of Chemistry, Wellesley College, 106 Central Street, Wellesley, Massachusetts 02481, United States
| | - Shao-Liang Zheng
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford St., Bauer B06, Cambridge, Massachusetts 02138, United States
| | - Tiffany Shou
- Department of Chemistry, Wellesley College, 106 Central Street, Wellesley, Massachusetts 02481, United States
| | - Ana Zeghibe
- Department of Chemistry, Wellesley College, 106 Central Street, Wellesley, Massachusetts 02481, United States
| | - Izzy Burdick
- Department of Chemistry, Wellesley College, 106 Central Street, Wellesley, Massachusetts 02481, United States
| | - Hannah Fuehrer
- Department of Chemistry, Wellesley College, 106 Central Street, Wellesley, Massachusetts 02481, United States
| | - Adrian Huang
- Department of Chemistry, Wellesley College, 106 Central Street, Wellesley, Massachusetts 02481, United States
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15
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Panwaria P, Das A. Understanding the n → π* non-covalent interaction using different experimental and theoretical approaches. Phys Chem Chem Phys 2022; 24:22371-22389. [PMID: 35822956 DOI: 10.1039/d2cp02070j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Herein, a perspective on the recent understanding of weak n → π* interaction obtained using different experimental and theoretical approaches is presented. This interaction is purely an orbital interaction that involves the delocalization of the lone pair electrons (n) on nitrogen, oxygen, and sulfur to the π* orbitals of CO, CN, and aromatic rings. The n → π* interaction has been found to profoundly influence the stabilization of peptides, proteins, drugs, and various small molecules. Although the functional properties of this non-covalent interaction are still quite underestimated, there are recent demonstrations of applying this interaction to the regulation of synthetic chemistry, catalysis, and molecular recognition. However, the identification and quantification of the n → π* interaction remain a demanding task as this interaction is quite weak and based on the electron delocalization between the two orbitals, while hyperconjugation interactions between neighboring atoms and the group involved in the n → π* interaction are simultaneously present. This review provides a comprehensive picture of understanding the n → π* interaction using different experimental approaches such as the X-ray diffraction technique, and electronic, NMR, microwave, and IR spectroscopy, in addition to quantum chemistry calculations. A detailed understanding of the n → π* interaction can help in modulating the strength of this interaction, which will be further helpful in designing efficient drugs, synthetic peptides, peptidomimetics, etc.
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Affiliation(s)
- Prakash Panwaria
- Department of Chemistry, Indian Institute of Science Education and Research (IISER) Pune, Dr. Homi Bhabha Road, Pashan, Pune-411008, India.
| | - Aloke Das
- Department of Chemistry, Indian Institute of Science Education and Research (IISER) Pune, Dr. Homi Bhabha Road, Pashan, Pune-411008, India.
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16
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Zondlo NJ. Solvation stabilizes intercarbonyl n→π* interactions and polyproline II helix. Phys Chem Chem Phys 2022; 24:13571-13586. [PMID: 35635541 DOI: 10.1039/d2cp00857b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
n→π* interactions between consecutive carbonyls stabilize the α-helix and polyproline II helix (PPII) conformations in proteins. n→π* interactions have been suggested to provide significant conformational biases to the disordered states of proteins. To understand the roles of solvation on the strength of n→π* interactions, computational investigations were conducted on a model n→π* interaction, the twisted-parallel-offset formaldehyde dimer, as a function of explicit solvation of the donor and acceptor carbonyls, using water and HF. In addition, the effects of urea, thiourea, guanidinium, and monovalent cations on n→π* interaction strength were examined. Solvation of the acceptor carbonyl significantly strengthens the n→π* interaction, while solvation of the donor carbonyl only modestly weakens the n→π* interaction. The n→π* interaction strength was maximized with two solvent molecules on the acceptor carbonyl. Urea stabilized the n→π* interaction via simultaneous engagement of both oxygen lone pairs on the acceptor carbonyl. Solvent effects were further investigated in the model peptides Ac-Pro-NMe2, Ac-Ala-NMe2, and Ac-Pro2-NMe2. Solvent effects in peptides were similar to those in the formaldehyde dimer, with solvation of the acceptor carbonyl increasing n→π* interaction strength and resulting in more compact conformations, in both the proline endo and exo ring puckers, as well as a reduction in the energy difference between these ring puckers. Carbonyl solvation leads to an energetic preference for PPII over both the α-helix and β/extended conformations, consistent with experimental data that protic solvents and protein denaturants both promote PPII. Solvation of the acceptor carbonyl weakens the intraresidue C5 hydrogen bond that stabilizes the β conformation.
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Affiliation(s)
- Neal J Zondlo
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA.
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17
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Lin B, Karki I, Pellechia PJ, Shimizu KD. Electrostatically-gated molecular rotors. Chem Commun (Camb) 2022; 58:5869-5872. [DOI: 10.1039/d2cc00512c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The ability to control molecular-scale motion using electrostatic interactions was demonstrated using an N-phenylsuccinimide molecular rotor with an electrostatic pyridyl-gate. Protonation of the pyridal-gate forms stabilizing electrostatic interactions in the...
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18
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Vik EC, Li P, Madukwe DO, Karki I, Tibbetts GS, Shimizu KD. Analysis of the Orbital and Electrostatic Contributions to the Lone Pair-Aromatic Interaction Using Molecular Rotors. Org Lett 2021; 23:8179-8182. [PMID: 34670094 DOI: 10.1021/acs.orglett.1c02878] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The attractive interaction between carbonyl oxygens and the π-face of aromatic surfaces was studied using N-phenylimide molecular rotors. The C═O···Ar interactions could stabilize the transition states but were half the strength of comparable C═O···C═O interactions. The C═O···Ar interaction had a significant electrostatic component but only a small orbital delocalization component.
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Affiliation(s)
- Erik C Vik
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Ping Li
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Daniel O Madukwe
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Ishwor Karki
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Gabriel S Tibbetts
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Ken D Shimizu
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
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19
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Deka JKR, Kalita D, Sahariah B, Sarma BK. n N → π* Ar interactions stabilize the E-ac isomers of arylhydrazides and facilitate their S NAr autocyclizations. Chem Commun (Camb) 2021; 57:11236-11239. [PMID: 34632997 DOI: 10.1039/d1cc04533d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We describe a novel mechanism of stabilization of the E-ac isomer of an arylhydrazide via nN → π*Ar interactions. We further show that when a leaving group (F) is present at the ortho-position of the carbonyl group of such an arylhydrazide, the nN → π*Ar interaction facilitates an SNAr autocyclization reaction to produce indazolone, an important heterocycle with biological activity. Faster autocyclization of arylhydrazide is observed when an electron withdrawing group is present in the aryl ring, which is a characteristic of SNAr reactions.
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Affiliation(s)
- Jugal Kishore Rai Deka
- Department of Chemistry, School of Natural Sciences, Shiv Nadar University, Dadri, Uttar Pradesh 201314, India
| | - Debajit Kalita
- New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Bangalore 560064, India.
| | - Biswajit Sahariah
- New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Bangalore 560064, India.
| | - Bani Kanta Sarma
- New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Bangalore 560064, India.
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20
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Wang W, Li X, Zhou PP, Wang Y. Catalysis with Supramolecular Carbon-Bonding Interactions. Angew Chem Int Ed Engl 2021; 60:22717-22721. [PMID: 34352156 DOI: 10.1002/anie.202108973] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 08/02/2021] [Indexed: 12/14/2022]
Abstract
Herein, we describe a new catalysis platform, supramolecular carbon-bonding catalysis, which exploits the highly directional weak interactions between carbon centers of catalysts and electron donors to drive chemical reactions. To demonstrate this catalysis approach, we discovered a class of cyclopropane derivatives incorporated with carbonyl, ester and cyano groups as catalysts which showed general catalysis capability in different types of benchmark reactions. Among these typical examples, a challenging tail-to-head terpene cyclization can be achieved by supramolecular carbon-bonding catalysis. The co-crystal structures of catalyst and electron donors, comparison experiments, and titrations support a catalysis mode of carbon-bonding activation of Lewis basic reactants.
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Affiliation(s)
- Wei Wang
- School of Chemistry and Chemical Engineering, Key Laboratory of the Colloid and Interface Chemistry, Ministry of Education, Shandong University, Jinan, 250100, China
| | - Xinxin Li
- School of Chemistry and Chemical Engineering, Key Laboratory of the Colloid and Interface Chemistry, Ministry of Education, Shandong University, Jinan, 250100, China
| | - Pan-Pan Zhou
- Key Laboratory of Advanced Catalysis of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, China
| | - Yao Wang
- School of Chemistry and Chemical Engineering, Key Laboratory of the Colloid and Interface Chemistry, Ministry of Education, Shandong University, Jinan, 250100, China.,State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100, China
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21
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Wang W, Li X, Zhou P, Wang Y. Catalysis with Supramolecular Carbon‐Bonding Interactions. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202108973] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Wei Wang
- School of Chemistry and Chemical Engineering Key Laboratory of the Colloid and Interface Chemistry Ministry of Education, Shandong University Jinan 250100 China
| | - Xinxin Li
- School of Chemistry and Chemical Engineering Key Laboratory of the Colloid and Interface Chemistry Ministry of Education, Shandong University Jinan 250100 China
| | - Pan‐Pan Zhou
- Key Laboratory of Advanced Catalysis of Gansu Province College of Chemistry and Chemical Engineering Lanzhou University Lanzhou 730000 China
| | - Yao Wang
- School of Chemistry and Chemical Engineering Key Laboratory of the Colloid and Interface Chemistry Ministry of Education, Shandong University Jinan 250100 China
- State Key Laboratory of Crystal Materials Shandong University Jinan 250100 China
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22
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Sahariah B, Sarma BK. Spectroscopic evidence of n → π* interactions involving carbonyl groups. Phys Chem Chem Phys 2021; 22:26669-26681. [PMID: 33226050 DOI: 10.1039/d0cp03557b] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
n → π* has emerged as an important noncovalent interaction that can affect the conformations of both small- and macromolecules including peptides and proteins. Carbonyl-carbonyl (COCO) n → π* interactions involving CO groups are well studied. Recent studies have shown that the COCO n → π* interactions are the most abundant secondary interactions in proteins with a frequency of 33 interactions per 100 residues and, among the various secondary interactions, n → π* interactions are expected to provide the highest enthalpic contributions to the conformational stability of globular proteins. However, n → π* interactions are relatively weak and provide an average stabilization of about 0.25 kcal mol-1 per interaction in proteins. The strongest n → π* interaction could be as strong as a moderate hydrogen bond. Therefore, it is challenging to detect and quantify these weak interactions, especially in solution in the presence of perturbation from other intermolecular interactions. Accordingly, spectroscopic investigations that can provide direct evidence of n → π* interaction are limited, and the majority of papers published in this area have relied on X-ray crystallography and/or theoretical calculations to establish the presence of this interaction. The aim of this perspective is to discuss the studies where a spectroscopic signature in support of n → π* interaction was observed. As the "n → π* interaction" is a relatively new terminology, there remains the possibility of there being earlier studies where spectroscopic evidence for n → π* interactions was obtained but it was not discussed in light of the n → π* terminology. We noticed several such studies and, as can be expected, these studies were often overlooked in the discussion of n → π* interactions in the recent literature. In this perspective, we have also discussed these studies and provided computational support for the presence of n → π* interaction.
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Affiliation(s)
- Biswajit Sahariah
- New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur, Bangalore 560064, India.
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23
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Elmi A, Cockroft SL. Quantifying Interactions and Solvent Effects Using Molecular Balances and Model Complexes. Acc Chem Res 2021; 54:92-103. [PMID: 33315374 DOI: 10.1021/acs.accounts.0c00545] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Where the basic units of molecular chemistry are the bonds within molecules, supramolecular chemistry is based on the interactions that occur between molecules. Understanding the "how" and "why" of the processes that govern molecular self-assembly remains an open challenge to the supramolecular community. While many interactions are readily examined in silico through electronic structure calculations, such insights may not be directly applicable to experimentalists. The practical limitations of computationally accounting for solvation is perhaps the largest bottleneck in this regard, with implicit solvation models failing to comprehensively account for the specific nature of solvent effects and explicit models incurring a prohibitively high computational cost. Since molecular recognition processes usually occur in solution, insight into the nature and effect of solvation is imperative not only for understanding these phenomena but also for the rational design of systems that exploit them.Molecular balances and supramolecular complexes have emerged as useful tools for the experimental dissection of the physicochemical basis of various noncovalent interactions, but they have historically been underexploited as a platform for the evaluation of solvent effects. Contrasting with large biological complexes, smaller synthetic model systems enable combined experimental and computational analyses, often facilitating theoretical analyses that can work in concert with experiment.Our research has focused on the development of supramolecular systems to evaluate the role of solvents in molecular recognition, and further characterize the underlying mechanisms by which molecules associate. In particular, the use of molecular balances has provided a framework to measure the magnitude of solvent effects and to examine the accuracy of solvent models. Such approaches have revealed how solvation can modulate the electronic landscape of a molecule and how competitive solvation and solvent cohesion can provide thermodynamic driving forces for association. Moreover, the use of simple model systems facilitates the interrogation and further dissection of the physicochemical origins of molecular recognition. This tandem experimental/computational approach has married less common computational techniques, like symmetry adapted perturbation theory (SAPT) and natural bonding orbital (NBO) analysis, with experimental observations to elucidate the influence of effects that are difficult to resolve experimentally (e.g., London dispersion and electron delocalization).
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Affiliation(s)
- Alex Elmi
- EaStCHEM School of Chemistry, University of Edinburgh, David Brewster Road, Edinburgh EH9 3FJ, United Kingdom
| | - Scott L. Cockroft
- EaStCHEM School of Chemistry, University of Edinburgh, David Brewster Road, Edinburgh EH9 3FJ, United Kingdom
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24
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Chen H, Tang X, Ye H, Wang X, Zheng H, Hai Y, Cao X, You L. Effects of n → π* Orbital Interactions on Molecular Rotors: The Control and Switching of Rotational Pathway and Speed. Org Lett 2020; 23:231-235. [PMID: 33351640 DOI: 10.1021/acs.orglett.0c03969] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The role of n → π* orbital interactions in the rotational pathway and barrier of biaryl-based molecular rotors was elucidated through a combined experimental and computational study. The n → π* interaction in the transition state can lead to the acceleration of rotors. The competition between the n → π* interaction and hydrogen bonding further enabled the reversal of the pathway and greasing/braking the rotor in response to acid/base stimuli, thereby creating a switchable molecular rotor.
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Affiliation(s)
- Hang Chen
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China
| | - Xiao Tang
- College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005,China
| | - Hebo Ye
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China
| | - Xinchang Wang
- College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005,China
| | - Hao Zheng
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China
| | - Yu Hai
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiaoyu Cao
- College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005,China
| | - Lei You
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China.,University of Chinese Academy of Sciences, Beijing 100049, China
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25
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Burns RJ, Mati IK, Muchowska KB, Adam C, Cockroft SL. Quantifying Through-Space Substituent Effects. Angew Chem Int Ed Engl 2020; 59:16717-16724. [PMID: 32542910 PMCID: PMC7540488 DOI: 10.1002/anie.202006943] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Indexed: 01/12/2023]
Abstract
The description of substituents as electron donating or withdrawing leads to a perceived dominance of through-bond influences. The situation is compounded by the challenge of separating through-bond and through-space contributions. Here, we probe the experimental significance of through-space substituent effects in molecular interactions and reaction kinetics. Conformational equilibrium constants were transposed onto the Hammett substituent constant scale revealing dominant through-space substituent effects that cannot be described in classic terms. For example, NO2 groups positioned over a biaryl bond exhibited similar influences as resonant electron donors. Meanwhile, the electro-enhancing influence of OMe/OH groups could be switched off or inverted by conformational twisting. 267 conformational equilibrium constants measured across eleven solvents were found to be better predictors of reaction kinetics than calculated electrostatic potentials, suggesting utility in other contexts and for benchmarking theoretical solvation models.
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Affiliation(s)
- Rebecca J. Burns
- EaStCHEM School of ChemistryUniversity of EdinburghJoseph Black BuildingDavid Brewster RoadEdinburghEH9 3FJUK
| | - Ioulia K. Mati
- EaStCHEM School of ChemistryUniversity of EdinburghJoseph Black BuildingDavid Brewster RoadEdinburghEH9 3FJUK
| | - Kamila B. Muchowska
- EaStCHEM School of ChemistryUniversity of EdinburghJoseph Black BuildingDavid Brewster RoadEdinburghEH9 3FJUK
| | - Catherine Adam
- EaStCHEM School of ChemistryUniversity of EdinburghJoseph Black BuildingDavid Brewster RoadEdinburghEH9 3FJUK
| | - Scott L. Cockroft
- EaStCHEM School of ChemistryUniversity of EdinburghJoseph Black BuildingDavid Brewster RoadEdinburghEH9 3FJUK
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26
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Kilgore HR, Olsson CR, D'Angelo KA, Movassaghi M, Raines RT. n→π* Interactions Modulate the Disulfide Reduction Potential of Epidithiodiketopiperazines. J Am Chem Soc 2020; 142:15107-15115. [PMID: 32701272 DOI: 10.1021/jacs.0c06477] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Epithiodiketopiperazines (ETPs) are a structurally complex class of fungal natural products with potent anticancer activity. In ETPs, the diketopiperazine ring is spanned by a disulfide bond that is constrained in a high-energy eclipsed conformation. We employed computational, synthetic, and spectroscopic methods to investigate the physicochemical attributes of this atypical disulfide bond. We find that the disulfide bond is stabilized by two n→π* interactions, each with large energies (3-5 kcal/mol). The n→π* interactions in ETPs make disulfide reduction much more difficult, endowing stability in physiological environments in a manner that could impact their biological activity. These data reveal a previously unappreciated means to stabilize a disulfide bond and highlight the utility of the n→π* interaction in molecular design.
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Affiliation(s)
- Henry R Kilgore
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Chase R Olsson
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Kyan A D'Angelo
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Mohammad Movassaghi
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Ronald T Raines
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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27
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Muchowska KB, Pascoe DJ, Borsley S, Smolyar IV, Mati IK, Adam C, Nichol GS, Ling KB, Cockroft SL. Reconciling Electrostatic and n→π* Orbital Contributions in Carbonyl Interactions. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202005739] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Kamila B. Muchowska
- EaStCHEM School of Chemistry The University of Edinburgh Joseph Black Building David Brewster Road Edinburgh EH9 3FJ UK
| | - Dominic J. Pascoe
- EaStCHEM School of Chemistry The University of Edinburgh Joseph Black Building David Brewster Road Edinburgh EH9 3FJ UK
| | - Stefan Borsley
- EaStCHEM School of Chemistry The University of Edinburgh Joseph Black Building David Brewster Road Edinburgh EH9 3FJ UK
| | - Ivan V. Smolyar
- EaStCHEM School of Chemistry The University of Edinburgh Joseph Black Building David Brewster Road Edinburgh EH9 3FJ UK
| | - Ioulia K. Mati
- EaStCHEM School of Chemistry The University of Edinburgh Joseph Black Building David Brewster Road Edinburgh EH9 3FJ UK
| | - Catherine Adam
- EaStCHEM School of Chemistry The University of Edinburgh Joseph Black Building David Brewster Road Edinburgh EH9 3FJ UK
| | - Gary S. Nichol
- EaStCHEM School of Chemistry The University of Edinburgh Joseph Black Building David Brewster Road Edinburgh EH9 3FJ UK
| | - Kenneth B. Ling
- Syngenta Jealott's Hill International Research Centre Bracknell Berkshire RG42 6EY UK
| | - Scott L. Cockroft
- EaStCHEM School of Chemistry The University of Edinburgh Joseph Black Building David Brewster Road Edinburgh EH9 3FJ UK
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28
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Muchowska KB, Pascoe DJ, Borsley S, Smolyar IV, Mati IK, Adam C, Nichol GS, Ling KB, Cockroft SL. Reconciling Electrostatic and n→π* Orbital Contributions in Carbonyl Interactions. Angew Chem Int Ed Engl 2020; 59:14602-14608. [PMID: 32485046 PMCID: PMC7496118 DOI: 10.1002/anie.202005739] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 05/29/2020] [Indexed: 12/16/2022]
Abstract
Interactions between carbonyl groups are prevalent in protein structures. Earlier investigations identified dominant electrostatic dipolar interactions, while others implicated lone pair n→π* orbital delocalisation. Here these observations are reconciled. A combined experimental and computational approach confirmed the dominance of electrostatic interactions in a new series of synthetic molecular balances, while also highlighting the distance-dependent observation of inductive polarisation manifested by n→π* orbital delocalisation. Computational fiSAPT energy decomposition and natural bonding orbital analyses correlated with experimental data to reveal the contexts in which short-range inductive polarisation augment electrostatic dipolar interactions. Thus, we provide a framework for reconciling the context dependency of the dominance of electrostatic interactions and the occurrence of n→π* orbital delocalisation in C=O⋅⋅⋅C=O interactions.
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Affiliation(s)
- Kamila B. Muchowska
- EaStCHEM School of ChemistryThe University of EdinburghJoseph Black BuildingDavid Brewster RoadEdinburghEH9 3FJUK
| | - Dominic J. Pascoe
- EaStCHEM School of ChemistryThe University of EdinburghJoseph Black BuildingDavid Brewster RoadEdinburghEH9 3FJUK
| | - Stefan Borsley
- EaStCHEM School of ChemistryThe University of EdinburghJoseph Black BuildingDavid Brewster RoadEdinburghEH9 3FJUK
| | - Ivan V. Smolyar
- EaStCHEM School of ChemistryThe University of EdinburghJoseph Black BuildingDavid Brewster RoadEdinburghEH9 3FJUK
| | - Ioulia K. Mati
- EaStCHEM School of ChemistryThe University of EdinburghJoseph Black BuildingDavid Brewster RoadEdinburghEH9 3FJUK
| | - Catherine Adam
- EaStCHEM School of ChemistryThe University of EdinburghJoseph Black BuildingDavid Brewster RoadEdinburghEH9 3FJUK
| | - Gary S. Nichol
- EaStCHEM School of ChemistryThe University of EdinburghJoseph Black BuildingDavid Brewster RoadEdinburghEH9 3FJUK
| | - Kenneth B. Ling
- SyngentaJealott's Hill International Research CentreBracknellBerkshireRG42 6EYUK
| | - Scott L. Cockroft
- EaStCHEM School of ChemistryThe University of EdinburghJoseph Black BuildingDavid Brewster RoadEdinburghEH9 3FJUK
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Burns RJ, Mati IK, Muchowska KB, Adam C, Cockroft SL. Quantifying Through‐Space Substituent Effects. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202006943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Rebecca J. Burns
- EaStCHEM School of ChemistryUniversity of EdinburghJoseph Black Building David Brewster Road Edinburgh EH9 3FJ UK
| | - Ioulia K. Mati
- EaStCHEM School of ChemistryUniversity of EdinburghJoseph Black Building David Brewster Road Edinburgh EH9 3FJ UK
| | - Kamila B. Muchowska
- EaStCHEM School of ChemistryUniversity of EdinburghJoseph Black Building David Brewster Road Edinburgh EH9 3FJ UK
| | - Catherine Adam
- EaStCHEM School of ChemistryUniversity of EdinburghJoseph Black Building David Brewster Road Edinburgh EH9 3FJ UK
| | - Scott L. Cockroft
- EaStCHEM School of ChemistryUniversity of EdinburghJoseph Black Building David Brewster Road Edinburgh EH9 3FJ UK
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30
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Vik EC, Li P, Maier JM, Madukwe DO, Rassolov VA, Pellechia PJ, Masson E, Shimizu KD. Large transition state stabilization from a weak hydrogen bond. Chem Sci 2020; 11:7487-7494. [PMID: 34123031 PMCID: PMC8159443 DOI: 10.1039/d0sc02806a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
A series of molecular rotors was designed to study and measure the rate accelerating effects of an intramolecular hydrogen bond. The rotors form a weak neutral O–H⋯O
Created by potrace 1.16, written by Peter Selinger 2001-2019
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C hydrogen bond in the planar transition state (TS) of the bond rotation process. The rotational barrier of the hydrogen bonding rotors was dramatically lower (9.9 kcal mol−1) than control rotors which could not form hydrogen bonds. The magnitude of the stabilization was significantly larger than predicted based on the independently measured strength of a similar O–H⋯OC hydrogen bond (1.5 kcal mol−1). The origins of the large transition state stabilization were studied via experimental substituent effect and computational perturbation analyses. Energy decomposition analysis of the hydrogen bonding interaction revealed a significant reduction in the repulsive component of the hydrogen bonding interaction. The rigid framework of the molecular rotors positions and preorganizes the interacting groups in the transition state. This study demonstrates that with proper design a single hydrogen bond can lead to a TS stabilization that is greater than the intrinsic interaction energy, which has applications in catalyst design and in the study of enzyme mechanisms. A series of molecular rotors was designed to study and measure the rate accelerating effects of an intramolecular hydrogen bond.![]()
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Affiliation(s)
- Erik C Vik
- Department of Chemistry and Biochemistry, University of South Carolina Columbia SC 29208 USA
| | - Ping Li
- Department of Chemistry and Biochemistry, University of South Carolina Columbia SC 29208 USA
| | - Josef M Maier
- Department of Chemistry and Biochemistry, University of South Carolina Columbia SC 29208 USA
| | - Daniel O Madukwe
- Department of Chemistry and Biochemistry, University of South Carolina Columbia SC 29208 USA
| | - Vitaly A Rassolov
- Department of Chemistry and Biochemistry, University of South Carolina Columbia SC 29208 USA
| | - Perry J Pellechia
- Department of Chemistry and Biochemistry, University of South Carolina Columbia SC 29208 USA
| | - Eric Masson
- Department of Chemistry and Biochemistry, Ohio University Athens OH 45701 USA
| | - Ken D Shimizu
- Department of Chemistry and Biochemistry, University of South Carolina Columbia SC 29208 USA
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Heywood VL, Alford TPJ, Roeleveld JJ, Lekanne Deprez SJ, Verhoofstad A, van der Vlugt JI, Domingos SR, Schnell M, Davis AP, Mooibroek TJ. Observations of tetrel bonding between sp 3-carbon and THF. Chem Sci 2020; 11:5289-5293. [PMID: 34122986 PMCID: PMC8159407 DOI: 10.1039/d0sc01559h] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
We report the direct observation of tetrel bonding interactions between sp3-carbons of the supramolecular synthon 3,3-dimethyl-tetracyanocyclopropane (1) and tetrahydrofuran in the gas and crystalline phase. The intermolecular contact is established via σ-holes and is driven mainly by electrostatic forces. The complex manifests distinct binding geometries when captured in the crystalline phase and in the gas phase. We elucidate these binding trends using complementary gas phase quantum chemical calculations and find a total binding energy of −11.2 kcal mol−1 for the adduct. Our observations pave the way for novel strategies to engineer sp3-C centred non-covalent bonding schemes for supramolecular chemistry. sp3-C⋯THF tetrel bonding was observed in the crystalline state and in the gas phase. Density functional calculations revealed interaction energies up to −11.2 kcal mol−1 and showed that these adducts are held together mainly by electrostatics.![]()
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Affiliation(s)
- Victoria L Heywood
- School of Chemistry, University of Bristol Cantock's Close Bristol BS8 1TS UK
| | - Thomas P J Alford
- School of Chemistry, University of Bristol Cantock's Close Bristol BS8 1TS UK
| | - Julius J Roeleveld
- van 't Hoff Institute for Molecular Sciences, Universiteit van Amsterdam Science Park 904 1098 XH Amsterdam The Netherlands
| | - Siebe J Lekanne Deprez
- van 't Hoff Institute for Molecular Sciences, Universiteit van Amsterdam Science Park 904 1098 XH Amsterdam The Netherlands
| | - Abraham Verhoofstad
- van 't Hoff Institute for Molecular Sciences, Universiteit van Amsterdam Science Park 904 1098 XH Amsterdam The Netherlands
| | - Jarl Ivar van der Vlugt
- van 't Hoff Institute for Molecular Sciences, Universiteit van Amsterdam Science Park 904 1098 XH Amsterdam The Netherlands .,Institute of Chemistry, Carl von Ossietzky University Oldenburg Carl-von-Ossietzky-Straße 9-11 D-12629 Oldenburg Germany
| | - Sérgio R Domingos
- Deutsches Elektronen-Synchrotron (DESY) Notkestraße 85 22607 Hamburg Germany
| | - Melanie Schnell
- Deutsches Elektronen-Synchrotron (DESY) Notkestraße 85 22607 Hamburg Germany.,Institut für Physikalische Chemie, Christian-Albrechts-Universität zu Kiel Max-Eyth-Str. 1 24118 Kiel Germany
| | - Anthony P Davis
- School of Chemistry, University of Bristol Cantock's Close Bristol BS8 1TS UK
| | - Tiddo J Mooibroek
- van 't Hoff Institute for Molecular Sciences, Universiteit van Amsterdam Science Park 904 1098 XH Amsterdam The Netherlands
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Chen H, Ye H, Hai Y, Zhang L, You L. n → π* interactions as a versatile tool for controlling dynamic imine chemistry in both organic and aqueous media. Chem Sci 2020; 11:2707-2715. [PMID: 34084329 PMCID: PMC8157614 DOI: 10.1039/c9sc05698j] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 01/31/2020] [Indexed: 11/21/2022] Open
Abstract
The imine bond holds a prominent place in supramolecular chemistry and materials science, and one issue is the stability of imines due to their electrophilic nature. Here we introduced ortho-carboxylate groups into a series of aromatic aldehydes/imines for dictating imine dynamic covalent chemistry (DCC) through n → π* interactions, one class of widespread and yet underused non-covalent interactions. The thermodynamically stabilizing role of carboxylate-aldehyde/imine n → π* interactions in acetonitrile was elucidated by the movement of the imine exchange equilibrium and further supported by crystal analysis. Computational studies provided mechanistic insights for n → π* interactions, the strength of which can surpass that of CH hydrogen bonding and is dependent on the orientation of interacting sites based on natural bond orbital analysis. Moreover, the substituent effect and the combination of recognition sites allowed additional means for modulation. Finally, to show the relevance of our findings ortho-carboxylate containing aldehydes were used to regulate imine formation/exchange in water, and modification of the N-terminus of amino acids and peptides was achieved in a neutral buffer. This work represents the latest example of weak interactions governing DCC and sets the stage for assembly and application studies.
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Affiliation(s)
- Hang Chen
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences Fuzhou 350002 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Hebo Ye
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences Fuzhou 350002 China
| | - Yu Hai
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences Fuzhou 350002 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Ling Zhang
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences Fuzhou 350002 China
| | - Lei You
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences Fuzhou 350002 China
- University of Chinese Academy of Sciences Beijing 100049 China
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