The inspiration and challenge for through-space charge transfer architecture: from thermally activated delayed fluorescence to non-linear optical properties

Organic molecules consisting of electron donor (D) and electron acceptor (A) subunits linked by π-conjugated bridges are promising building blocks for thermally activated delayed fluorescence (TADF) and non-linear optics (NLO) materials due to their intramolecular charge transfer (CT) processes in response to external stimuli. According to the electron interaction pattern, the CT process in D-π-A architectures can be divided into two categories, through-bond/-space charge transfer (TB/TSCT). To date, research into the TADF properties of TSCT characteristic molecules has since seen significant growth. In fact, TSCT characteristic materials show great advantages in such NLO responses. In this perspective, we first briefly introduced the basic principles of NLO and TADF effects. Successively, we discuss the influence of TBCT and TSCT patterns on NLO and TADF properties, especially for TSCT characteristic. In the final part, we address the diversity and potential advantages of TSCT characteristic molecules as high-performance NLO materials. With these, it is expected that the greater structural flexibility of spatial conjugation can bring more functionality to NLO materials in the future.

Synthesis of hyperpolarizable biomaterials at molecular level based on pyridinium–chitosan complexes

Novel types of fluorescent and quaternized pyridinium–chitosan derivatives have been synthesized and their characteristics as potential NLO-phore biomaterials have been disclosed by DFT calculations.

Static second hyperpolarizability of Λ shaped alkaline earth metal complexes

A number of Λ shaped complexes of alkaline earth metals Be , Mg and Ca with varying terminal groups have been considered for the theoretical study of their second hyperpolarizability. The chosen complexes are found to be sufficiently stable and for a chosen ligand the stability decreases in the order: Be -complex > Ca -complex > Mg -complex. The calculated results of second hyperpolarizability obtained at different DFT functionals for the 6-311++G(d,p) basis set are found to be fairly consistent. The Λ shaped ligands upon complex formation with metals lead to strong enhancement of second hyperpolarizability. The highest magnitude of cubic polarizability has been predicted for the metal complex having > C ( C 2 H 5)2 group. For a chosen ligand, the magnitude of second hyperpolarizability increases in the order Be -complex < Mg -complex < Ca -complex which is the order of increasing size and electropositive character of the metal. The variation of second hyperpolarizability among the investigated metal complexes has been explained in terms of the transition energy and transition moment associated with the most intense electronic transition.