COORDINATION ENVIRONMENT STRATEGY FOR MOLYBDENUM(V) PORPHYRIN COMPLEXES TO IMPROVE THEIR SENSORY PARAMETERS

Molybdenum(V) porphyrin complexes, O=Mo(X)P (P is a substituted porphine, X is a single-charged anionic ligand), show affinity to practically significant organic bases, give an accessible for registration spectral response in the UV-visible region and therefore have prospects as active components of sensor devices. In order to achieve high values of the sensory parameters, the present work analyzes the influence of the composition of the O=Mo(X)P coordination sphere on them by varying the axial ligand X and the substituent in the composition of the equatorial macrocyclic ligand. For this purpose, a complete kinetic description of the reaction with pyridine (Py), a classical example of highly volatile organic compounds (VOCs), proceeding as two consecutive two-way reactions, identification and characterization of the intermediate and final products by UV-visible, H NMR, IR spectroscopy and mass spectrometry, and sensing activity parameters — time and numerical value of the spectral response to the presence of Py and the lower limit of determination of the latter is presented using oxo(5,10,15,20-tetraphenylporphinato)(ethoxy)molybdenum(V) (O=Mo(OEt)TPP) as an example. Using similar data for O=Mo(OH)TPP, O=Mo(OEt)TTP and O=Mo(OEt)TBuPP (TTP and TBuPP are dianions of tetra-4-methyl- and tetra-4-tert-butyl-substituted TPP, respectively), it is shown that the directed formation of the coordination sphere is a means for fine-tuning the sensory properties and that the complex O=Mo(OEt)TPP is the most effective in this capacity.