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 creatinine detection in aqueous and biological media. Probe 1, bearing terminal electron-withdrawing –CN substituents, exhibited superior photostability, reduced aggregation, and stronger emission (λ_max = 430 nm) compared to unsubstituted Probe 2 (λ_max = 430 nm). Creatinine triggered a dual optical response: Soret-band hypochromicity and far-red fluorescence quenching via hydrogen-bond-driven ground-state complexation, with a binding constant of K_b = 1.25 × 10⁴ M⁻¹ for Probe 1 and 4.154 × 10³ M⁻¹ for Probe 2. Microenvironment-controlled spectroscopy, FT-IR, DLS, and SEM confirmed N–H⋯O/N hydrogen-bonded adducts and aggregate formation as the dominant mechanism. Probe 1 achieved a low limit of detection (LOD = 0.017 µM; 3σ/k) in buffer, enabling semi-quantitative analysis of creatinine (0–50 µM) in diluted human urine with minimal matrix interference. This structurally tunable porphyrinic platform integrates robust optical signatures with biologically relevant recognition, promising point-of-care renal biomarker monitoring.