Hydrogen-Bonding Mediated Supramolecular Assembly of Fluorescent Meso-Aryl Porphyrins for Creatinine Monitoring in Biological Samples

Abstract

Herein, we report the design, synthesis, and mechanistic evaluation of two meso-aryl free-base porphyrins for selective detection of creatinine in aqueous as well as in biological media. Probe 1, with terminal electron-withdrawing –CN substituents, displayed enhanced photostability, reduced aggregation, and markedly stronger emission relative to unsubstituted Probe 2. Creatinine induces a dual optical response comprising hypochromicity in Soret-bands and far-red fluorescence quenching, arising from hydrogen-bond–driven ground-state complexation with creatinine, leading to supramolecular aggregation. Microenvironment-controlled spectroscopic investigations, along with FT-IR, DLS, and SEM analyses, confirm the formation of N–H···O/N hydrogen-bonded adducts and subsequent aggregate growth as the primary sensing mechanism. Further, Probe 1 enabled semi-quantitative analysis of creatinine in diluted human urine, exhibiting linear quantification with minimal matrix interference. The study demonstrates a structurally tunable porphyrinic platform that couples strong optical signatures with biologically relevant recognition, offering promise for point-of-care renal biomarker monitoring.