Metameric influences on conformational selectivity for zwitterionic pyridinium cyclopentadienide and its aza analogues. Quantum mechanical studies on linear and nonlinear optoelectronic properties

This contribution reports the structure–property correlations for few already synthesized bi-aryl types of zwitterionic molecules. Quantum mechanical methodologies like, HF, MP2, B3LYP, CAM-B3LYP, LC-ωPBE, M06-2X, and ωB97xD were used to investigate the optoelectronic properties of some interesting metameric pairs, where the molecules were bonded either through Reichardt's or Brooker's modes. Different bonding modes and inter-ring attractive forces are assigned to investigate three distinct cases (i) metameric enforcements & preferential resonance stabilizations, (ii) inter-ring hydrogen bonded stabilizations through hetero-atoms in the ring, and (iii) an amalgamation of these two forces. Computations indicate unusual structural preferences (planar vs. twisted) by the metameric pairs, and thus direct reflections of these behaviors on some of the important tensorial properties like, dipole moments, polarizabilities, hyperpolarizabilities, and so forth were observed. The metameric manipulation on structure–property correlations shown by these molecules can be utilized as useful strategies for efficient chromophore design, not only in the field of nonlinear optics, but also in other areas of research connecting to advanced functional materials for technological applications.