Photosensitization Ability of 1,7-Phenanthroline Based Bis−BODIPYs: Perplexing Role of Intramolecular Rotation on Photophysical Properties

Abstract

1,7Phenanthroline based bisboron dipyrromethenes (bisBODIPYs) B1 and B2 obtained via small substitutional changes (Cl/SCH3) have been described. The effect of RIR in emission enhancement in a viscous solvent (glycerol) has been studied besides vital role of intermolecular interactions scrutinized by Xray single crystal studies. The efficiency of intersystem crossing (ISC) in generation of singlet oxygen (ΦΔ∼ 19.2% and 56.7%) by photoirradiation using visible light along with distinct photostability has been investigated by 1,3-diphenylisobenzofuran (DPBF) titration studies. The 1O2 generation quantum yield and photosensitizing durability of the bisBODIPYs have been investigated by photooxidation of 1,5-dihydroxynaphthalene (DHN) in presence of B1 and B2 as photosensitizers. The pseudo-first-order rate constants for photooxidation reactions and consumption rates of DHN reflected appreciable 1O2 generation quantum yields (ΦΔ: B1, 29.0; B2, 57.8%). Density functional theory (DFT) studies showed distri...