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Synthesis and structural study of organic two‐photon‐absorbing cycloalkanone chromophores
Author(s) -
Bogdanov Georgii,
Tillotson John P.,
Khrustalev Victor N.,
Rigin Sergei,
Timofeeva Tatiana V.
Publication year - 2019
Publication title -
acta crystallographica section c
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 17
ISSN - 2053-2296
DOI - 10.1107/s2053229619014360
Subject(s) - chemistry , intermolecular force , molecule , crystallography , steric effects , alkane stereochemistry , chromophore , cyclopentanone , hydrogen bond , ring (chemistry) , stereochemistry , intramolecular force , crystal structure , photochemistry , catalysis , organic chemistry
The three organic two‐photon‐absorbing cycloalkanone chromophores 2,4‐bis[4‐(diethylamino)benzylidene]cyclobutanone, C 26 H 32 N 2 O ( I ), 2,5‐bis[4‐(diethylamino)benzylidene]cyclopentanone, C 27 H 34 N 2 O ( II ), and 2,6‐bis[4‐(diethylamino)benzylidene]cyclohexanone, C 28 H 36 N 2 O ( III ), were obtained by a reaction between 4‐(diethylamino)benzaldehyde and the corresponding cycloalkanone and were characterized by single‐crystal X‐ray diffraction studies, as well as density functional theory (DFT) quantum‐chemical calculations. Molecules of this series have three main fragments, i.e. central acceptor ( A ) and two terminal donors ( D 1 and D 2 ) and represent examples of the D 1 –π– A –π– D 2 molecular design. All three compounds crystallize with two crystallographically independent molecules in the asymmetric unit ( A and B ) and are distinguished by the conformations of both the molecular Et 2 N—C 6 H 4 —C=C—C(=O)—C=C—C 6 H 4 —NEt 2 backbone (arcuate or linear) and the terminal diethylamino substituents (syn‐ or antiperiplanar to the plane of the molecule). The central four‐ and five‐membered rings in I and II are almost planar, and the six‐membered ring in III adopts a sofa conformation. In the crystals of I – III , the two independent molecules A and B form hydrogen‐bonded [ A … B ] dimers via intermolecular C—H…O hydrogen bonds. Furthermore, the [ A … B ] dimers in I are bound by intermolecular C—H…O hydrogen bonds into two‐tier puckered layers, whereas in the crystals of II and III , the [ A … B ] dimers are stacked along the c and a axes, respectively. Taking into account the decreasing steric strain upon expanding the central ring, compound I might be more efficient as a two‐photon absorption chromophore than compounds II and III , which corresponds to the results of spectroscopic studies.