Surface‐Modified Phthalocyanine‐Based Two‐Dimensional Conjugated Metal–Organic Framework Films for Polarity‐Selective Chemiresistive Sensing

Abstract 2D conjugated metal–organic frameworks (2D c ‐MOFs) are emerging as electroactive materials for chemiresistive sensors, but selective sensing with fast response/recovery is a challenge. Phthalocyanine‐based Ni 2 MPc(NH) 8 2D c ‐MOF films are presented as active layers for polarity‐selective chemiresisitors toward water and volatile organic compounds (VOCs). Surface‐hydrophobic modification by grafting aliphatic alkyl chains on 2D c ‐MOF films decreases diffused analytes into the MOF backbone, resulting in a considerably accelerated recovery progress (from ca. 50 to ca. 10 s) during humidity sensing. Toward VOCs, the sensors deliver a polarity‐selective response among alcohols but no signal for low‐polarity aprotic hydrocarbons. The octadecyltrimethoxysilane‐modified Ni 2 MPc(NH) 8 based sensor displays high‐performance methanol sensing with fast response (36 s)/recovery (13 s) and a detection limit as low as 10 ppm, surpassing reported room‐temperature chemiresistors.