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. 2023 Jul 26;28(15):5646.
doi: 10.3390/molecules28155646.

Photoswitchable Molecular Units with Tunable Nonlinear Optical Activity: A Theoretical Investigation

Aggelos Avramopoulos  1 , Heribert Reis  2 , Demeter Tzeli  3   4 , Robert Zaleśny  5 , Manthos G Papadopoulos  2
Affiliations

Photoswitchable Molecular Units with Tunable Nonlinear Optical Activity: A Theoretical Investigation

Aggelos Avramopoulos et al. Molecules. .

Abstract

The first-, second-, and third-order molecular nonlinear optical properties, including two-photon absorption of a series of derivatives, involving two dithienylethene (DTE) groups connected by several molecular linkers (bis(ethylene-1,2-dithiolato)Ni- (NiBDT), naphthalene, quasilinear oligothiophene chains), are investigated by employing density functional theory (DFT). These properties can be efficiently controlled by DTE switches, in connection with light of appropriate frequency. NiBDT, as a linker, is associated with a greater contrast, in comparison to naphthalene, between the first and second hyperpolarizabilities of the "open-open" and the "closed-closed" isomers. This is explained by invoking the low-lying excited states of NiBDT. It is shown that the second hyperpolarizability can be used as an index, which follows the structural changes induced by photochromism. Assuming a Förster type transfer mechanism, the intramolecular excited-state energy transfer (EET) mechanism is studied. Two important parameters related to this are computed: the electronic coupling (VDA) between the donor and acceptor fragments as well as the overlap between the absorption and emission spectra of the donor and acceptor groups. NiBDT as a linker is associated with a low electronic coupling, VDA, value. We found that VDA is affected by molecular geometry. Our results predict that the linker strongly influences the communication between the open-closed DTE groups. The sensitivity of the molecular nonlinear optical properties could assist with identification of molecular isomers.

Keywords: (hyper)polarizability; bis(ethylene-1,2-dithiolato); density functional theory; dithienylethene; excited-state energy transfer; molecular switches; photochromism; two-photon absorption.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
The structures of 1cc, 1co, and 1oo computed using the B3LYP/6-31G* method.
Figure 2
Figure 2
The structures of 2oo, 2oc, 2cc, 3oo, and 3oc, computed using the B3LYP/6-31G* method.
Figure 2
Figure 2
The structures of 2oo, 2oc, 2cc, 3oo, and 3oc, computed using the B3LYP/6-31G* method.
Figure 3
Figure 3
The considered dimers (left fragment: donor; right fragment: acceptor.
Figure 4
Figure 4
The absorption (black line) and the emission spectra (red, green, and blue lines) of the 2oc fragments (left fragment: donor, right fragment: acceptor). The CAMB3LYP/6-31G* method was used.
Figure 5
Figure 5
Calculated open–open (2oo), open–closed (2oc), and closed–closed (2cc) structures at CAM-B3LYP/6-31G* H,C,O,F,S ECP28MWB(SDD)Ni.
Figure 6
Figure 6
NIR-vis-UV absorption (solid line) and emission (dotted line) spectra of the 2oo, 2oc, and 2cc structures at CAM-B3LYP/6-31G* H,C,O,F,S ECP28MWB(SDD)Ni level of theory. (Peak half-width at half height: 0.09 eV).
Figure 7
Figure 7
Frontier molecular orbitals (MO) involving in the main absorption and emission excitations of 2oo. (a) absorption excitation of the a conformer (b) absorption excitation of the b conformer.
Figure 8
Figure 8
Frontier molecular orbitals (MO) involving in the main absorption and emission excitations of 2oc.
Figure 9
Figure 9
Frontier molecular orbitals (MO) involving in the main absorption excitations of 2cc.
See this image and copyright information in PMC

References

    1. Fihey A., Russo R., Cupellini L., Jacquemin D., Mennucci B. Is energy transfer limiting multiphotochromism? answers from ab initio quantifications. Phys. Chem. Chem. Phys. 2017;19:2044–2052. doi: 10.1039/C6CP07458H. - DOI - PubMed
    1. Galanti A., Santoro J., Mannancherry R., Duez Q., Diez-Cabanes V., Valasek M., De Winter J., Cornil J., Gerbaux P., Mayor M., et al. A New Class of Rigid Multi(azobenzene) Switches Featuring Electronic Decoupling: Unravelling the Isomerization in Individual Photochromes. J. Am. Chem. Soc. 2019;141:9273–9283. doi: 10.1021/jacs.9b02544. - DOI - PubMed
    1. Hsu C.P. The Electronic Couplings in Electron Transfer and Excitation Energy Transfer. Acc. Chem. Res. 2009;42:509–518. doi: 10.1021/ar800153f. - DOI - PubMed
    1. Nakamura Y., Aratani N., Osuka A. Cyclic porphyrin arrays as artificial photosynthetic antenna: Synthesis and excitation energy transfer. Chem. Soc. Rev. 2007;36:831–845. doi: 10.1039/b618854k. - DOI - PubMed
    1. Zhang L.Y., Friesner R.A., Murphy R.B. Ab initio quantum chemical calculation of electron transfer matrix elements for large molecules. J. Chem. Phys. 1997;107:450–459. doi: 10.1063/1.474406. - DOI

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