Appending zinc tetraphenylporphyrin with an amine receptor at β-pyrrolic carbon for designing a selective histamine chemosensor

Adopting the rarely used β-functionalisation strategy in porphyrin-based sensor design, an amine receptive site is appended onto the zinc(II) porphyrin molecular framework affording a ditopic chemosensor 4. The assembled chemosensor interacts selectively with histamine in toluene via a 'two-site' binding mode. Association constant of the complex evaluated from the respective UV-vis spectra is found to be (2.32 ± 0.57) × 10⁶, which is approximately 4-fold greater than those complexes derived from 4 and nicotine/histidine. On the basis of a combined spectroscopic method and molecular modelling, the binding model of the porphyrin host and biogenic guest molecules is established. Our results clearly demonstrate the viability of the design and development of the porphyrin-based chemosensor by appending a receptor at the β-pyrrolic carbon of the porphyrin scaffold.