An Organic Receptor Isolated in an Unusual Intermediate Conformation: Computation, Crystallography, and Hirshfeld Surface Analysis

作者：Naik Indravath Krishna; Sarkar Rudraditya; Madhu Vedichi; Bolligarla Ramababu; Kishore Ravada; Das Samar K^*

来源：Journal of Physical Chemistry A, 2017, 121(17): 3274-3286.

DOI：10.1021/acs.jpca.7b00091

1,1"-1,4-Phenylene-bis(methylene)bis-4,4'-bipyridinium cation [C28H24N4](2+) (c), an organic receptor that generally crystallizes in its anti conformation, has recently been shown to be isolated in its syn conformation in an ion paired compound [C28H24N4][Zn(dmit)(2)]center dot 2DMF (dmit(2-) = 1,3-dithiole-2-thione-4,5-dithiolate; DMF = dimethylformamide). In this article, we demonstrated that the same receptor [C28H24N4](2) (c) can also be stabilized in an unusual intermediate conformation (neither syn nor anti) with PF6- anion in compound [C28H24N4](PF6)(2)-(1,4-dioxane) (1 center dot(1,4-dioxane)). The energetically favored anti conformation has been described in its nitrate salt [C28H24N4](NO3)(2)center dot 2H(2)O (2 center dot 2H(2)O). Compounds 1 center dot(1,4-dioxane)and 2 center dot 2H(2)O, crystallizing in triclinic and monoclinic systems with space groups P (1) over bar and P2(1)/n, respectively, were additionally characterized by Hirshfeld surface analysis. The density functional theory calculations are performed to understand the internal mechanism of the stability of various conformers of cationic receptor c, compound 1, and compound 2. In conjunction with the electronic stability of the conformers, the natural bond orbital analysis and conformational equilibrium constants at different temperatures are also calculated to find out the sources of the different stability of the various conformers of experimentally synthesized compounds.

• 出版日期2017-5-4