1-Alkyl-2-(arylazo)imidazoles: Unique Combination of Photochromic and Liquid Crystal properties

Abhisake Karmakar1

Debashis Mallick2

Chandana Sen3

Chittaranjan Sinha1,Email

1Department of Chemistry, Jadavpur University, Kolkata,700 032, West Bengal.

2Mrinalini Datta Mahavidyapith, Birati, 700 051, West Bengal.

3Behala College, Kolkata, 700 060, West Bengal.

 

Abstract

Photochromism and Liquid Crystals are mainly dominated by the change of structure/orientation upon optical/thermal stimulation. Upon light absorption photochromic molecules show reversible structural change with eligible spectral features. The molecules who transform from the orientational more ordered to less ordered arrangement by thermal/physical stimuli show the properties of LC or mesogen. Photochromic responses in LCs encourage re-alignments upon light irradiation and various other properties of the materials. Photochromism is a disorder phenomenon while LC is an ordered orientation; hence, the design of single molecule with two contradicting properties is challenging. Azobenzenes belong to unique class of photochrome and undergo trans-cis photoisomerization while presence of long aliphatic chains sometime induces the LC properties. In our research, a series of substituted arylazoimidazoles are designed and some of them are susceptible to optical stimulation and a few of the long alkyl substituted 1-Alkyl-2-(arylazo)imidazoles (Raai-CnH2n) show thermally controlled LC behaviour.

 1-Alkyl-2-(arylazo)imidazoles: Unique Combination of Photochromic and Liquid Crystal properties