Nanomaterials - 11

Abstract

Isomers are molecules with the same chemical formula but different atom or functional group arrangements. Physical and chemical properties of these isomers are very similar and very difficult to identify. Therefore, the detection and differentiation of such isomers often require a tandem separation method equipped with sophisticated advanced detection techniques. Such techniques such HPLC-MS, Ion Mobility Mass Spectrometry (IM-MS), NMR are super expensive and need trained person for operation. Xylene is one of the most important examples with three different isomers and industrially very important. Along with xylene, benzene, toluene, which are collectively known as BTX gases are used extensively in many industrial products and very toxic in nature. Development of low-cost, portable and easy to use sensors for such isomer detection or toxic component detection in their gas or vapour phase is very important. In this regard, membrane-type surface stress sensor (MSS)1 could be excellent option if we have very sensitive receptor layer which can selectively detect targeted analytes and can operate in the wide range of humidity. Here, we have developed a novel class of materials based on non-planar saddle-shaped N-heterocycle-fused metalloporphyrin, which are highly soluble in common organic solvent and forms a persistent microporous crystalline structure upon solvent evaporation.2, 3 These unique receptor materials are highly sensitive due to their strong interaction with the MSS membrane and special arrangement of different functional groups inside the porous cavity is responsible for excellent selectivity to different targeted gas/VOCs. Additionally, fine tuning of functional groups of the metallo-porphyrin structure allows control of the receptor microporosity and chemical environment pores resulting in different selectivity. Finally, performance under high humid (100 % RH) condition of our receptor layer and can be used to discriminate different low concentrated targeted analytes, volatile isomers even in their mixtures. Thus, we have developed a series of receptor materials which are highly porous, solution processable and ready to deposit on any suitable sensor platform for use as receptor materials for gas or VOC sensing.