Photorelease of nitric oxide in water-soluble diruthenium nitrosyl complexes with phosphonate substituted pyridylpyrrole

The diethylphosphonate ligand HL1 substituted pyridylpyrrole was synthesized by treatment of 2-bromo-6-(1H'-pyrrol-2-yl)pyridine and diethylphosphite in presence of base triethylamine and catalyst Pd(PPh3)4 under refluxing toluene conditions. The HL1 ligand was treated with bromotrimethylsilane and followed by hydrolysis with methanol to afford the diphosphonic acid ligand H3L2. Treatment of H3L2 with [Ru(NO)Cl-3] in presence of triethylamine in refluxing thf was generated diruthenium nitrosyl complex [Ru(L-2)(NO)(Cl)](2)center dot (Et3NH)(2) ([1]center dot (Et3NH)(2)), which is water soluble. The ligands and metal complex were fully characterized by NMR, IR, ESI-MS and single crystal X-ray diffraction technology. The solid-state structure analysis displays 1(2-) is dinuclear species, of which two ruthenium atoms are linked by two PO(3)(2-)groups. Photorelease of nitric oxide from 1(2-) was monitored by UV-Vis spectra and the amount of the NO was determined by the Griess reaction and DPPH radical scavenging reaction.

Automated summary

In this study, a diethylphosphonate ligand substituted with pyridylpyrrole was successfully synthesized and converted into a diphosphonic acid ligand through a reaction and hydrolysis. A water-soluble diruthenium nitrosyl complex was generated using [Ru(NO)Cl-3] and triethylamine. The released nitric oxide was monitored and quantified using spectroscopy and chemical reactions.