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Photoswitchable nonlinear optical properties of azobenzene-based supramolecular complexes: insights from density functional theory
Ist Teil von
Physical chemistry chemical physics : PCCP, 2023-08, Vol.25 (3), p.243-245
Ort / Verlag
England: Royal Society of Chemistry
Erscheinungsjahr
2023
Link zum Volltext
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
Density functional theory (DFT) calculations were performed for a series of supramolecular assemblies containing azobenzene (Azo-X where X = I, Br and H) and alkoxystilbazole subunits to evaluate their electronic, linear and nonlinear optical properties. These assemblies are derivatives of azobenzene, obtained by the substitution of electron-withdrawing and electron-donating groups onto the molecular skeleton. The interaction energies (
E
int
) of all the designed supramolecular complexes (
IA-IF
,
IIA-IIF
and
IIIA-IIIF
) range from −1.0 kcal mol
−1
to −7.7 kcal mol
−1
. The electronic properties of these hydrogen/halogen bond driven supramolecular assemblies such as vertical ionization energies (VIE), HOMO-LUMO energy gap (
G
H-L
), excitation energies, density of states (DOS) and natural population (NPA) analyses were also computed. The non-covalent interaction index (NCI) and quantum theory of atoms in molecules (QTAIM) analyses were also performed to validate the nature of inter- and intra-molecular interactions in these complexes. A substantial enhancement in the first hyperpolarizability (
β
0
) values of the designed supramolecular complexes was observed, which is driven by the charge transfer from the pyridyl moiety of alkoxystilbazole to Azo-X. The highest
β
0
value of 1.3 × 10
4
au was observed for the supramolecular complex of
p
-nitro substituted azobenzene with alkoxystilbazole (
ID
complex). Moreover, the results show that the substitution of electron-withdrawing groups on Azo-X can also bring larger
β
0
values for such complexes. It was confirmed on a purely theoretical basis that both the types of noncovalent interactions present and the substituent group incorporated influence the nonlinear optical (NLO) response of the systems. Furthermore, the
β
0
values of the
E
(
trans
) and
Z
(
cis
) forms were compared to demonstrate the two-way photoinduced switching mechanism.
Highly efficient photoswitchable frequency doublers, based on noncovalent interactions between azobenzene and alkoxystilbazole, are explored using DFT calculations.