New Molecular Chemosensors Based on Niobium(V) 5,10,15,20-(Tetra-4-tert-butylphenyl)porphine for Detection of VOCs

Resumo

Reactions of pyridine (Py) with (5,10,15,20-(tetra-4-tert-butylphenyl)porphinato)trichloroniobium(V) (Nb(Cl)₃T^tBuPP) and H⁺-bonded Nb(Cl)₃T^tBuPP (Nb(Cl)₃T^tBuPP···H⁺···Cl⁻) in toluene have been studied using spectroscopy (UV-vis, IR, ¹H NMR, mass spectrometry, fluorescence), thermodynamics and kinetics. The process is a system of consecutive two- and one-way reactions of the two pyridine molecules bonding; the nature of this interactions is determined by the chemical structure of the initial niobium(V) porphyrin. The reactions have been completely quantitatively described, and the intermediate and final products spectral parameters used for the product chemical structure confirmation have been determined. It has been demonstrated that Nb(Cl)₃T^tBuPP and Nb(Cl)₃T^tBuPP···H⁺···Cl⁻ are good candidates for use as optical and fluorescent chemosensors of VOCs (volatile organic compounds) and nitrogenous bases—building blocks of pharmaceuticals, food components, and environmental pollutants—with the following parameters: the stability constant of the complex with pyridine K = (1.99 ± 0.3) × 10⁴ L²/mol² and (2.8 ± 0.5) × 10² L/mol, relative optical response A = 0.91 and 0.35, detection limit of Py 1.74 × 10^–3 and 4.05 × 10^–4 mol/L, respectively. The results are applicable for use in the design of dye-sensitized solar cells (DSSCs) since the reaction studied is a model for self-assembly of donor–acceptor systems based on metalloprorphyrins and pyridyl derivatives of carbon nanoforms.