TITLE:
Design, Synthesis, Crystal Structure and Photophysical Properties of New Oxadiazole Extended Viologen Fluorophore
AUTHORS:
Tetsuji Moriguchi, Masataka Okuyama, Venkataprasad Jalli
KEYWORDS:
Oxadiazole Extended Methyl Viologen, Bipyridine Oxadiazole, Crystal Struc-ture, Pyridine-4-Carboxy Aldehyde, Isonicotinic Acid Hydrazide, Fluorescence
JOURNAL NAME:
Crystal Structure Theory and Applications,
Vol.10 No.2,
March
5,
2021
ABSTRACT: Viologens
(N,N'-dimethyl-4,4-bipyridinium) are advanced functional materials,
found important applications in electrochromic devices, molecular machines,
organic batteries, and carbohydrate oxidation catalysts in alkaline fuel. In
this article, we investigated the design, synthesis and photophysical properties
of N,N'-dimethyl-2,5-Bis(pyridinium)oxadiazole 4 and its
precursor 2,5- Bis(pyridine)oxadiazole 2. The crystal structure and photophysical properties of viologen 4 and precursor 2 have been
determined. The viologen molecule 4 crystallized in monoclinic form,
space group P21/n with four molecules in unit cell.
Precursor molecule 2 also crystalized in monoclinic form, space group C2/c with four molecules in unit cell. From
X-rd data, we found three cations in the molecular structure of viologen
molecule 4, which is unusual in viologens. In the three-dimensional
molecular packing diagram of molecule 4, the three cations and iodate
anions are stabilized by C···C, C···I, N···I, N···H, H···I, N—H···I and
C—H···I. The dihedral angle between planes having oxadiazole and two benzene
rings are 5° and 8°, suggesting the molecule 4 is a slightly strained
one. The molecular structure of precursor molecule 2 stabilized by C···C
and N···H short contacts between the molecules. The molecule 4 displayed
strong absorbance at 315 nm and emissions between 390 - 410 nm.