A thiazolo[5,4-d]thiazole-bridged porphyrin organic framework as a promising nonlinear optical material

Porphyrin-based porous organic frameworks are an important group of materials gaining interest due to their structural diversity and distinct opto-electronic properties. However, these materials are seldom explored for nonlinear optical (NLO) applications. In this work, we investigate a thiazolo[5,4-d]thiazole-bridged porous, porphyrin framework (Por-TzTz-POF) with promising NLO properties. The planar TzTz moiety coupled with integrated porphyrin units enables efficient pi-conjugation and charge distribution in the Por-TzTz-POF resulting in a high nonlinear absorption coefficient (beta = 1100 cm GW(-1)) with figure of merit (FoM) sigma(1)/sigma(0) = 5571, in contrast to analogous molecules and material counterparts e.g. metal-organic frameworks (MOFs; beta = similar to 0.3-0.5 cm GW(-1)), molecular porphyrins (beta = similar to 100-400 cm GW(-1)), graphene (beta = 900 cm GW(-1)), and covalent organic frameworks (Por-COF-HH; beta = 1040 cm GW(-1) and FoM = 3534).