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 π-conjugation and charge distribution in the Por-TzTz-POF resulting in a high nonlinear absorption coefficient (β = 1100 cm GW^-1) with figure of merit (FoM) σ₁/σ₀ = 5571, in contrast to analogous molecules and material counterparts e.g. metal-organic frameworks (MOFs; β = ∼0.3-0.5 cm GW^-1), molecular porphyrins (β = ∼100-400 cm GW^-1), graphene (β = 900 cm GW^-1), and covalent organic frameworks (Por-COF-HH; β = 1040 cm GW^-1 and FoM = 3534).