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Amonov A, Scheiner S. Halogen Bonding to the π-Systems of Polycyclic Aromatics. Chemphyschem 2024:e202400482. [PMID: 38923736 DOI: 10.1002/cphc.202400482] [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: 04/27/2024] [Revised: 06/06/2024] [Accepted: 06/26/2024] [Indexed: 06/28/2024]
Abstract
The propensity of the π-electron system lying above a polycyclic aromatic system to engage in a halogen bond is examined by DFT calculations. Prototype Lewis acid CF3I is placed above the planes of benzene, naphthalene, anthracene, phenanthrene, naphthacene, chrysene, triphenyl, pyrene, and coronene. The I atom positions itself some 3.3-3.4 Å above the polycyclic plane, and the associated interaction energy is about 4 kcal/mol. This quantity is a little smaller for benzene, but is roughly equal for the larger polycyclics. The energy only oscillates a little as the Lewis acid slides across the face of the polycyclic, preferring regions of higher π-electron density over minima of the electrostatic potential. The binding is dominated by dispersion which contributes half of the total interaction energy.
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Affiliation(s)
- Akhtam Amonov
- Department of Optics and Spectroscopy, Institute of Engineering Physics Samarkand State University, University blv. 15, 140104, Samarkand, Uzbekistan
| | - Steve Scheiner
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah, 84322-0300, USA
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Devore DP, Ellington TL, Shuford KL. Elucidating the Role of Electron-Donating Groups in Halogen Bonding. J Phys Chem A 2024; 128:1477-1490. [PMID: 38373286 DOI: 10.1021/acs.jpca.3c06894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2024]
Abstract
Computational quantum chemical techniques were utilized to systematically examine how electron-donating groups affect the electronic and spectroscopic properties of halogen bond donors and their corresponding complexes. Unlike the majority of studies on halogen bonding, where electron-withdrawing groups are utilized, this work investigates the influence of electron-donating substituents within the halogen bond donors. Statistical analyses were performed on the descriptors of halogen bond donors in a prescribed set of archetype, halo-alkyne, halo-benzene, and halo-ethynyl benzene halogen bond systems. The σ-hole magnitude, binding and interaction energies, and the vibrational X···N local force constant (where X = Cl, Br, I, and At) were found to correlate very well in a monotonic and linear manner with all other properties studied. In addition, enhanced halogen bonds were found when the systems contained electron-donating groups that could form intramolecular hydrogen bonds with the electronegative belt of the halogen atom and adjacent linker features.
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Affiliation(s)
- Daniel P Devore
- Department of Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, Texas 76798-7348, United States
| | - Thomas L Ellington
- Department of Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, Texas 76798-7348, United States
| | - Kevin L Shuford
- Department of Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, Texas 76798-7348, United States
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Lakhera S, Rana M, Devlal K. Comprehensive quantum chemical study of the associative complex of para-aminobenzoic acid and 7-diethylamino 4-methyl coumarin by adsorption and aromatic bridges. J Mol Model 2024; 30:37. [PMID: 38212580 DOI: 10.1007/s00894-023-05816-w] [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: 10/12/2023] [Accepted: 12/20/2023] [Indexed: 01/13/2024]
Abstract
CONTEXT The present study accounts for the quantum chemical and nonlinear optical properties of the combination of para-aminobenzoic acid and 7-diethylamino 4-methyl coumarin. Three different complexes were designed, surface interaction (adsorption) and two by connecting both molecules with π-bridge benzene and biphenyl. The amino and carboxyl groups were observed to behave as strong donor and acceptor sites in all the complexes. The band gap of the adsorbed complex was found more suitable. The absorption wavelength and intensity both were seen to increase with the increase in the number of benzene rings in the π-bridge. The values of first- and second-order hyperpolarizability suggest the improved nonlinear optical responses of the introduced complexes. Additionally, the negative value of second-order hyperpolarizability suggests the possibility of the occurrence of reverse saturable absorption in these combinations. The reported work gives theoretical insights into the nonlinear optical properties of the combination of para-aminobenzoic acid and 7-diethylamino 4-methyl coumarin. METHODS The molecular modeling and the quantum chemical studies were performed with Gaussian software packages. The standard B3LYP-6-311++G(d,p) basis functionals were used for energy minimization and other spectral calculations. All the surface analyses reported here are obtained by employing Multiwfn software. The chemical reactivity was established by the global reactivity descriptors. The intramolecular interactions and charge localization were stated using inter-fragment charge transfer analysis.
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Affiliation(s)
- Shradha Lakhera
- Department of Physics, School of Sciences, Uttarakhand Open University, Haldwani, Uttarakhand, 263139, India
| | - Meenakshi Rana
- Department of Physics, School of Sciences, Uttarakhand Open University, Haldwani, Uttarakhand, 263139, India.
| | - Kamal Devlal
- Department of Physics, School of Sciences, Uttarakhand Open University, Haldwani, Uttarakhand, 263139, India
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Scheiner S, Michalczyk M, Zierkiewicz W. Influence of Internal Angular Arrangement on Pnicogen Bond Strength. Inorg Chem 2023. [PMID: 38016913 DOI: 10.1021/acs.inorgchem.3c03141] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2023]
Abstract
The three Z-X covalent bonds of a ZX3 unit (Z = P, As, Sb, Bi) are normally arranged in a pyramidal structure. Quantum chemical calculations show that pnicogen bonds (ZBs) to the central Z are weakened if ZX3 is flattened, as in the opening of an umbrella. The partial closing of the umbrella has the opposite effect of substantially strengthening these ZBs, even amounting to a 2- or 3-fold magnification in certain cases. The strongest such bonds, wherein Sb and Bi are in a strained configuration within a ZO3CH model system, have interaction energies of 20 kcal/mol with an NH3 base. Most of these systems, whether flattened or more pyramidal, are capable of engaging in three ZBs simultaneously, despite a certain amount of negative cooperativity.
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Affiliation(s)
- Steve Scheiner
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322-0300, United States
| | - Mariusz Michalczyk
- Faculty of Chemistry, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Wiktor Zierkiewicz
- Faculty of Chemistry, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
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Abstract
The properties of the bond between a N-ligand and a Lewis acid containing a σ-hole are studied by quantum chemical methods. Interactions considered include pnicogen bonds involving SbX5, PX5, and PX3, where X represents any of the halogen atoms F, Cl, Br, or I. Also studied are the tetrel bonds of PbX4 and SiX4, as well as the chalcogen bond involving TeOX4. Both NH3 and NCH are applied as two possible bases of differing potency. Some of the bonds are very strong with interaction energies easily exceeding 25 kcal/mol and with AIM bond critical point densities much higher than 0.04 au, suggesting their classification as coordinate covalent bonds. The pentavalent SbX5 and PX5 fall into this category when combined with NH3, as does TeOX4. Although the tetrel bonds involving PbX4 are only slightly weaker, they are probably better viewed as a strong noncovalent bond on the cusp of covalency. Changing the internal bonding of hypervalent SbX5 to the more conventional SbX3 weakens the interaction to a classical noncovalent pnicogen bond. Reducing the base nucleophilicity from NH3 to NCH weakens the bonds so that they are clearly noncovalent.
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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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Amonov A, Scheiner S. Relation between Halogen Bond Strength and IR and NMR Spectroscopic Markers. Molecules 2023; 28:7520. [PMID: 38005241 PMCID: PMC10673387 DOI: 10.3390/molecules28227520] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 11/04/2023] [Accepted: 11/08/2023] [Indexed: 11/26/2023] Open
Abstract
The relationship between the strength of a halogen bond (XB) and various IR and NMR spectroscopic quantities is assessed through DFT calculations. Three different Lewis acids place a Br or I atom on a phenyl ring; each is paired with a collection of N and O bases of varying electron donor power. The weakest of the XBs display a C-X bond contraction coupled with a blue shift in the associated frequency, whereas the reverse trends occur for the stronger bonds. The best correlations with the XB interaction energy are observed with the NMR shielding of the C atom directly bonded to X and the coupling constants involving the C-X bond and the C-H/F bond that lies ortho to the X substituent, but these correlations are not accurate enough for the quantitative assessment of energy. These correlations tend to improve as the Lewis acid becomes more potent, which makes for a wider range of XB strengths.
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Affiliation(s)
- Akhtam Amonov
- Department of Optics and Spectroscopy, Engineering Physics Institute, Samarkand State University, University blv. 15, Samarkand 140104, Uzbekistan;
| | - Steve Scheiner
- Department of Chemistry and Biochemistry, Utah State University, Logan, UT 84322-0300, USA
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Amonov A, Scheiner S. Heavy pnicogen atoms as electron donors in sigma-hole bonds. Phys Chem Chem Phys 2023; 25:23530-23537. [PMID: 37656119 DOI: 10.1039/d3cp03479h] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
Abstract
DFT calculations evaluate the strength of σ-hole bonds formed by ZH3 and ZMe3 (Z = N, P, As, Sb) acting as electron donor. Bond types considered include H-bond, halogen, chalcogen, pnicogen, and tetrel bond to perfluorinated Lewis acids FH, FBr, F2Se F3As, F4Ge, respectively, as well as their monofluorinated analogues. All of the Z atoms can engage in bonds of at least moderate strength, varying from 3 to more than 40 kcal mol-1. In most cases, N forms the strongest bonds, but the falloff from P to Sb is quite mild. However, this pattern is not characteristic of all cases, as for example in the halogen bonds, where the heavier Z atoms are comparable to, or even stronger than N. Most of the bonds are strengthened by replacing the three H atoms of ZH3 by methyl groups, better simulating the situation that would be generally encountered. Structural and NMR shielding data ought to facilitate the identification of these bonds within crystals or in solution.
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Affiliation(s)
- Akhtam Amonov
- Department of Optics and Spectroscopy Engineering Physics Institute, Samarkand State University, University blv. 15, Samarkand 140104, Uzbekistan
| | - Steve Scheiner
- Department of Chemistry and Biochemistry, Utah State University Logan, Utah 84322-0300, USA.
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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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Amonov A, Scheiner S. Competition between Binding to Various Sites of Substituted Imidazoliums. J Phys Chem A 2023. [PMID: 37490696 DOI: 10.1021/acs.jpca.3c04097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/27/2023]
Abstract
The imidazolium cation has a number of different sites that can interact with a nucleophile. Adding a halogen atom (X) or a chalcogen (YH) group introduces the possibility of an NX···nuc halogen or NY···nuc chalcogen bond, which competes against the various H-bonds (NH and CH donors) as well as the lone pair···π interaction wherein the nucleophile lies above the plane of the cation. Substituted imidazoliums are paired with the NH3 base, and the various different complexes are evaluated by density functional theory (DFT) calculations. The strength of XB and YB increases quickly along with the size and polarizability of the X/Y atom, and this sort of bond is the strongest for the heavier Br, I, Se, and Te atoms, followed by the NH···N H-bond, but this order reverses for Cl and S. The various CH···N H-bonds are comparable to one another and to the lone pair···π bond, all with interaction energies of 10-13 kcal/mol, values which show very little dependence upon the substituent placed on the imidazolium.
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Affiliation(s)
- Akhtam Amonov
- Department of Optics and Spectroscopy, Engineering Physics Institute, Samarkand State University, University blv. 15, Samarkand 140104, Uzbekistan
| | - Steve Scheiner
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322-0300, United States
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Abstract
Quantum calculations study the potential of an intramolecular H-bond between the halogen atom (X) of a halobenzene and a substituent placed ortho to it, to amplify the ability of X to engage in a halogen bond (XB) with a Lewis base. H-bonding substituents NH2, CH2CH2OH, CH2OH, OH, and COOH were added to halobenzenes (X = Cl, Br, I). The amino group had little effect, but those containing OH increased the CX···N XB energy to a NH3 nucleophile by about 0.5 kcal/mol; the increment associated with COOH is larger, nearly 2 kcal/mol. These energy increments were approximately doubled if two such H-bonding substituents are present. Combining a pair of ortho COOH groups with an electron-withdrawing NO2 group in the para position has a particularly large effect, raising the XB energy by about 4 kcal/mol, which can amount to as much as a 4-fold magnification.
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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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