1
|
Chen CY, Chai JD. Effect of Oriented External Electric Fields on the Electronic Properties of Linear Acenes: A Thermally Assisted Occupation DFT Study. Molecules 2024; 29:4245. [PMID: 39275093 PMCID: PMC11396984 DOI: 10.3390/molecules29174245] [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: 08/18/2024] [Revised: 08/31/2024] [Accepted: 09/05/2024] [Indexed: 09/16/2024] Open
Abstract
Recently, oriented external electric fields (OEEFs) have earned much attention due to the possibility of tuning the properties of electronic systems. From a theoretical perspective, one can resort to electronic structure calculations to understand how the direction and strength of OEEFs affect the properties of electronic systems. However, for multi-reference (MR) systems, calculations employing the popular Kohn-Sham density functional theory with the traditional semilocal and hybrid exchange-correlation energy functionals can yield erroneous results. Owing to its decent compromise between accuracy and efficiency for MR systems at the nanoscale (i.e., MR nanosystems), in this study, thermally assisted occupation density functional theory (TAO-DFT) is adopted to explore the electronic properties of n-acenes (n = 2-10), containing n linearly fused benzene rings, in OEEFs, where the OEEFs of various electric field strengths are applied along the long axes of n-acenes. According to our TAO-DFT calculations, the ground states of n-acenes in OEEFs are singlets for all the cases examined. The effect of OEEFs is shown to be significant on the vertical ionization potentials and vertical electron affinities of ground-state n-acenes with odd-number fused benzene rings. Moreover, the MR character of ground-state n-acenes in OEEFs increases with the increase in the acene length and/or the electric field strength.
Collapse
Affiliation(s)
- Chi-Yu Chen
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan
| | - Jeng-Da Chai
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan
- Center for Theoretical Physics and Center for Quantum Science and Engineering, National Taiwan University, Taipei 10617, Taiwan
- Physics Division, National Center for Theoretical Sciences, Taipei 10617, Taiwan
| |
Collapse
|
2
|
Somani A, Gupta D, Bettinger HF. Computational Studies of Dimerization of [ n]-Cyclacenes. J Phys Chem A 2024; 128:6847-6852. [PMID: 39133933 PMCID: PMC11345815 DOI: 10.1021/acs.jpca.4c02833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Revised: 07/09/2024] [Accepted: 07/23/2024] [Indexed: 08/23/2024]
Abstract
Cyclacenes, C4nH2n, consist of n linearly fused benzene rings that are arranged to result in a closed nanohoop structure. Cyclacenes are thus the cyclic versions of acenes and have so far escaped synthesis. In order to estimate the tendency of [n]-cyclacenes (6 ≤ n ≤ 20) to undergo dimerization, which is assumed to be a major pathway of degradation under oxygen-free conditions, we here report the energy of dimerization as computed by density functional theory using spin-restricted, spin-unrestricted, and thermally assisted-occupation (TAO) formalisms. It is found that the energy of dimerization increases with increasing size of n but that this increase is not monotonic for the smaller members of the series. This is due to the combination of the cryptoannulenic effect and the inherent strain of the cyclacenes. The energy of dimerization of the largest member inspected, [20]-cyclacene, is -59.3 kcal/mol, while we expect it to converge to -46 kcal/mol for n → ∞ based on comparison with data obtained for acenes.
Collapse
Affiliation(s)
- Ankit Somani
- Institut für Organische
Chemie, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 18, Tübingen 72076, Germany
| | - Divanshu Gupta
- Institut für Organische
Chemie, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 18, Tübingen 72076, Germany
| | - Holger F. Bettinger
- Institut für Organische
Chemie, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 18, Tübingen 72076, Germany
| |
Collapse
|
3
|
Huang X, Gan PY, Gao FW, Su ZM. Tuning optical properties of π-conjugated double nanohoops under external electric field stimuli-responsiveness. Phys Chem Chem Phys 2024; 26:8716-8723. [PMID: 38416055 DOI: 10.1039/d3cp05504c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/29/2024]
Abstract
Carbon nanorings have attracted substantial interest from synthetic chemists due to their unique topological structures and distinct physical properties. An intriguing π-conjugated double-nanoring structure, denoted as [8]CPP-[10]cyclacene, was constructed via the integration of [8]cycloparaphenylene ([8]CPP) into [10]cyclacene. Using the external electric field stimuli-responsiveness of [8]CPP-[10]cyclacene, directional charge transfer can be induced, resulting in the emergence of intriguing properties. The effects of the external electric field in three specific directions were explored, vertically in the [8]CPP unit (Fy), vertically in the [10]cyclacene unit (Fz), and horizontally along the double nanorings diameter (Fx). Interestingly, the external electric field vertically to the [10]cyclacene unit significantly enhanced the first hyperpolarizability (βtot) compared to that vertically to the [8]CPP unit. Notably, [8]CPP-[10]cyclacene under Fx exhibited significantly larger the βtot values (1.48 × 105 a.u.) than those of vertical Fy and Fz. This work opens up a wide range of nonlinear optics, making it a compelling area to explore in the field of carbon nanomaterials.
Collapse
Affiliation(s)
- Xiao Huang
- School of Chemistry and Environmental Engineering, Changchun University of Science and Technology, 7989 Weixing Road, Changchun 130012, China
| | - Ping-Yao Gan
- School of Chemistry and Environmental Engineering, Changchun University of Science and Technology, 7989 Weixing Road, Changchun 130012, China
| | - Feng-Wei Gao
- School of Chemistry and Environmental Engineering, Changchun University of Science and Technology, 7989 Weixing Road, Changchun 130012, China
- Chongqing Research Institute, Changchun University of Science and Technology, No. 618 Liangjiang Avenue, Longxing Town, Yubei District, Chongqing City 401135, China.
| | - Zhong-Min Su
- School of Chemistry and Environmental Engineering, Changchun University of Science and Technology, 7989 Weixing Road, Changchun 130012, China
- State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, College of Chemistry, Jilin University, Changchun 130021, China.
| |
Collapse
|
4
|
Ruan Z, Schramm J, Bauer JB, Naumann T, Bettinger HF, Tonner-Zech R, Gottfried JM. Synthesis of Tridecacene by Multistep Single-Molecule Manipulation. J Am Chem Soc 2024; 146:3700-3709. [PMID: 38216144 PMCID: PMC10870776 DOI: 10.1021/jacs.3c09392] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 12/23/2023] [Accepted: 12/27/2023] [Indexed: 01/14/2024]
Abstract
Acenes represent a unique class of polycyclic aromatic hydrocarbons that have fascinated chemists and physicists due to their exceptional potential for use in organic electronics. While recent advances in on-surface synthesis have resulted in higher acenes up to dodecacene, a comprehensive understanding of their fundamental properties necessitates their expansion toward even longer homologues. Here, we demonstrate the on-surface synthesis of tridecacene via atom-manipulation-induced conformational preparation and dissociation of a trietheno-bridged precursor on a Au(111) surface. The generated tridecacene has been investigated by scanning tunneling microscopy and spectroscopy (STM/STS), combined with first-principles calculations. We observe that the STS transport gap (1.09 eV) shrinks again following the gap reopening of dodecacene (1.4 eV). Spin-polarized density functional theory calculations confirm an antiferromagnetic open-shell ground-state electronic configuration for tridecacene in the gas phase. Interestingly, tridecacene's open-shell character is significantly reduced upon interaction with the Au(111) surface despite being only physisorbed. The interaction with the surface leads to a lowering of the magnetization of tridecacene, a reduced gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), compared to the gas phase, and a reduced relative energy to the nonmagnetic state, making it nearly isoenergetic. These observations show qualitatively that the influence of the Au(111) substrate on the properties of long acenes is significant, which is important for interpreting the measured STS transport gaps. Our work contributes to a fundamental understanding of the electronic properties of long acenes, confirming a nonmonotonous length-dependent HOMO-LUMO gap, and to the development of multistep tip-assisted synthesis of elusive compounds.
Collapse
Affiliation(s)
- Zilin Ruan
- Fachbereich
Chemie, Philipps-Universität Marburg, Hans-Meerwein-Str. 4, 35032 Marburg, Germany
| | - Jakob Schramm
- Universität
Leipzig, Fakultät für Chemie und Mineralogie, Wilhelm-Ostwald-Institut für Physikalische
und Theoretische Chemie, Linnéstraße 2, 04103 Leipzig, Germany
| | - John B. Bauer
- Institut
für Organische Chemie, Universität
Tübingen, Auf
der Morgenstelle 18, 72076 Tübingen, Germany
| | - Tim Naumann
- Fachbereich
Chemie, Philipps-Universität Marburg, Hans-Meerwein-Str. 4, 35032 Marburg, Germany
| | - Holger F. Bettinger
- Institut
für Organische Chemie, Universität
Tübingen, Auf
der Morgenstelle 18, 72076 Tübingen, Germany
| | - Ralf Tonner-Zech
- Universität
Leipzig, Fakultät für Chemie und Mineralogie, Wilhelm-Ostwald-Institut für Physikalische
und Theoretische Chemie, Linnéstraße 2, 04103 Leipzig, Germany
| | - J. Michael Gottfried
- Fachbereich
Chemie, Philipps-Universität Marburg, Hans-Meerwein-Str. 4, 35032 Marburg, Germany
| |
Collapse
|
5
|
Seenithurai S, Chai JD. Electronic Properties of Graphene Nano-Parallelograms: A Thermally Assisted Occupation DFT Computational Study. Molecules 2024; 29:349. [PMID: 38257262 PMCID: PMC11154290 DOI: 10.3390/molecules29020349] [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: 12/18/2023] [Revised: 01/05/2024] [Accepted: 01/08/2024] [Indexed: 01/24/2024] Open
Abstract
In this computational study, we investigate the electronic properties of zigzag graphene nano-parallelograms (GNPs), which are parallelogram-shaped graphene nanoribbons of various widths and lengths, using thermally assisted occupation density functional theory (TAO-DFT). Our calculations revealed a monotonic decrease in the singlet-triplet energy gap as the GNP length increased. The GNPs possessed singlet ground states for all the cases examined. With the increase of GNP length, the vertical ionization potential and fundamental gap decreased monotonically, while the vertical electron affinity increased monotonically. Some of the GNPs studied were found to possess fundamental gaps in the range of 1-3 eV, lying in the ideal region relevant to solar energy applications. Besides, as the GNP length increased, the symmetrized von Neumann entropy increased monotonically, denoting an increase in the degree of the multi-reference character associated with the ground state GNPs. The occupation numbers and real-space representation of active orbitals indicated that there was a transition from the nonradical nature of the shorter GNPs to the increasing polyradical nature of the longer GNPs. In addition, the edge/corner localization of the active orbitals was found for the wider and longer GNPs.
Collapse
Affiliation(s)
- Sonai Seenithurai
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan;
| | - Jeng-Da Chai
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan;
- Center for Theoretical Physics and Center for Quantum Science and Engineering, National Taiwan University, Taipei 10617, Taiwan
- Physics Division, National Center for Theoretical Sciences, Taipei 10617, Taiwan
| |
Collapse
|
6
|
Tsai HY, Chai JD. Real-Time Extension of TAO-DFT. Molecules 2023; 28:7247. [PMID: 37959667 PMCID: PMC10647330 DOI: 10.3390/molecules28217247] [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: 09/27/2023] [Revised: 10/19/2023] [Accepted: 10/21/2023] [Indexed: 11/15/2023] Open
Abstract
Thermally assisted occupation density functional theory (TAO-DFT) has been an efficient electronic structure method for studying the ground-state properties of large electronic systems with multi-reference character over the past few years. To explore the time-dependent (TD) properties of electronic systems (e.g., subject to an intense laser pulse), in this work, we propose a real-time (RT) extension of TAO-DFT, denoted as RT-TAO-DFT. Moreover, we employ RT-TAO-DFT to study the high-order harmonic generation (HHG) spectra and related TD properties of molecular hydrogen H2 at the equilibrium and stretched geometries, aligned along the polarization of an intense linearly polarized laser pulse. The TD properties obtained with RT-TAO-DFT are compared with those obtained with the widely used time-dependent Kohn-Sham (TDKS) method. In addition, issues related to the possible spin-symmetry breaking effects in the TD properties are discussed.
Collapse
Affiliation(s)
- Hung-Yi Tsai
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan;
| | - Jeng-Da Chai
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan;
- Center for Theoretical Physics and Center for Quantum Science and Engineering, National Taiwan University, Taipei 10617, Taiwan
- Physics Division, National Center for Theoretical Sciences, Taipei 10617, Taiwan
| |
Collapse
|
7
|
Seenithurai S, Chai JD. TAO-DFT with the Polarizable Continuum Model. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:nano13101593. [PMID: 37242010 DOI: 10.3390/nano13101593] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 05/07/2023] [Accepted: 05/08/2023] [Indexed: 05/28/2023]
Abstract
For the ground-state properties of gas-phase nanomolecules with multi-reference character, thermally assisted occupation (TAO) density functional theory (DFT) has recently been found to outperform the widely used Kohn-Sham DFT when traditional exchange-correlation energy functionals are employed. Aiming to explore solvation effects on the ground-state properties of nanomolecules with multi-reference character at a minimal computational cost, we combined TAO-DFT with the PCM (polarizable continuum model). In order to show its usefulness, TAO-DFT-based PCM (TAO-PCM) was used to predict the electronic properties of linear acenes in three different solvents (toluene, chlorobenzene, and water). According to TAO-PCM, in the presence of these solvents, the smaller acenes should have nonradical character, and the larger ones should have increasing polyradical character, revealing striking similarities to the past findings in the gas phase.
Collapse
Affiliation(s)
- Sonai Seenithurai
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan
| | - Jeng-Da Chai
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan
- Center for Theoretical Physics and Center for Quantum Science and Engineering, National Taiwan University, Taipei 10617, Taiwan
- Physics Division, National Center for Theoretical Sciences, Taipei 10617, Taiwan
| |
Collapse
|
8
|
Synthesis of the [11]Cyclacene Framework by Repetitive Diels-Alder Cycloadditions. Molecules 2021; 26:molecules26103047. [PMID: 34065279 PMCID: PMC8161356 DOI: 10.3390/molecules26103047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 05/11/2021] [Accepted: 05/14/2021] [Indexed: 11/16/2022] Open
Abstract
The Diels–Alder cycloaddition between bisdienes and bisdienophile incorporating the 7-oxa-bicyclo[2.2.1]heptane unit are well known to show high diastereoselectivity that can be exploited for the synthesis of molecular belts. The related bisdiene 5,6,7,8-tetramethylidene-2-bicyclo[2.2.2]octene is a valuable building block for the synthesis of photoprecursors for acenes, but it has not been employed for the synthesis of molecular belts. The present work investigates by computational means the Diels–Alder reaction between these bisdiene building blocks with syn-1,4,5,8-tetrahydro-1,4:5,8-diepoxyanthracene, which shows that the diastereoselectivity of the Diels–Alder reaction of the etheno-bridged bisdiene is lower than that of the epoxy-bridged bisdiene. The reaction of the etheno-bridged bisdiene and syn-1,4,5,8-tetrahydro-1,4:5,8-diepoxyanthracene in 2:1 ratio yields two diastereomers that differ in the orientation of the oxa and etheno bridges based on NMR and X-ray crystallography. The all-syn diastereomer can be transformed into a molecular belt by inter- and intramolecular Diels–Alder reactions with a bifunctional building block. The molecular belt could function as a synthetic intermediate en route to a [11]cyclacene photoprecursor.
Collapse
|
9
|
Gupta D, Omont A, Bettinger HF. Energetics of Formation of Cyclacenes from 2,3-Didehydroacenes and Implications for Astrochemistry. Chemistry 2021; 27:4605-4616. [PMID: 33372718 PMCID: PMC7986185 DOI: 10.1002/chem.202003045] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 08/12/2020] [Indexed: 01/01/2023]
Abstract
The carriers of the diffuse interstellar bands (DIBs) are still largely unknown although polycyclic aromatic hydrocarbons, carbon chains, and fullerenes are likely candidates. A recent analysis of the properties of n-acenes of general formula C4n+2 H2n+4 suggested that these could be potential carriers of some DIBs. Dehydrogenation reactions of n-acenes after absorption of an interstellar UV photon may result in dehydroacenes. Here the reaction energies and barriers for formation of n-cyclacenes from 2,3-didehydroacenes (n-DDA) by intramolecular Diels-Alder reaction to dihydro-etheno-cyclacenes (n-DEC) followed by ejection of ethyne by retro-Diels-Alder reactions are analyzed using thermally assisted occupation density functional theory (TAO-DFT) for n=10-20. It is found that the barriers for each of the steps depend on the ring strain of the underlying n-cyclacene, and that the ring strain of n-DEC is about 75 % of that of the corresponding n-cyclacene. In each case, ethyne extrusion is the step with the highest energy barrier, but these barriers are smaller than CH bond dissociation energies, suggesting that formation of cyclacenes is an energetically conceivable fate of n-acenes after multiple absorption of UV photons.
Collapse
Affiliation(s)
- Divanshu Gupta
- Institut für Organische ChemieUniversität TübingenAuf der Morgenstelle 1872076TübingenGermany
| | - Alain Omont
- Institut d'Astrophysique de ParisSorbonne Université, UPMC Université Paris 6 and CNRS, UMR 709598bis boulevard Arago75014ParisFrance
| | - Holger F. Bettinger
- Institut für Organische ChemieUniversität TübingenAuf der Morgenstelle 1872076TübingenGermany
| |
Collapse
|