Isomeric Benzenediol-Linked Organophosphonates as a Handy Reusable Emitting Platform: Diversity in Polyamine Vapor Detection

Abstract

This work introduces metal/column-free facile quantitative access to conformationally twisted catechol-linked organophosphonate (CAP) as a blue-emitting solid that could reversibly detect only 1,3-diaminopropane (DAP) and 1,2ethylenediamine (EDA) vapors, belonging to industrially and pharmaceutically abundant crucial diamines. In CAP, two adjacent hydroxy groups in a benzene ring facilitate selective diamine−dihydroxy (amine−phenol type) interactions in the solid phase, leading to a quenched emission with selectively smaller aliphatic PAs, that is, DAP and EDA. The disparity was noticed with an isomeric resorcinol-linked emitter (RAP), detecting various polyamine vapors with superior sensitivity. A one-carbon-away placed hydroxy group in RAP can only generate a monoamine−hydroxy complex, not diamine−dihydroxy. The more acidic nature of resorcinol would prefer ionizing the amines and, consequently, creating amine/hydroxy interactions. More systematic investigations reveal an exciting role of amine−hydroxy realization for the catechol analog in the solid phase with a syn−anti conformation for CAP. Unlike CAP, RAP's available crystal void space creates considerable room in which to come closer and facilitates amine− phenol interactions. The role of phosphonates in the selective detection of PAs is also examined. Observed outcomes are substantiated by FT-IR, single-crystal X-ray diffraction, SEM, XPS, and mass spectroscopic studies. The proposed amine−hydroxy interactions are further supported by DFT-optimized molecular structures.