TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The dehydrating agent used is selected from aluminum phosphate, N,N'-dicyclohexylcarbodiimide, iron(III) chloride, orthoformic acid, phosphorus pentoxide, and phosphoryl chloride. The transition metal in metal-(bpy)2Cl2.2H2O complex is selected from ruthenium (II) and osmium (II).    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation (claimed): Preparing resorcinol bound transition metal-pyridyl ligand complex of formula I involves: (i) treating 4,4'-dimethyl-2,2'-bipyridine with lithium diisopropyl amide, followed by coupling at 5 degrees C to (-)40 degrees C with 3,5-dimethoxybenzaldehyde in organic solvent, to obtain precursor alcohol of formula (7); (ii) dehydrating alcohol of step (i) in presence of base to afford 4-(3,5-dimethoxystyryl)-4'-methyl-2,2'-bipyridine of formula (1), followed by demethylation at 130-230 degrees C with molten pyridinium hydrochloride to obtain 5-(2-(4'-methyl-2,2'-bipyridin-4-yl)vinyl)benzene-1,3-diol of formula (2); (iii) treating 5-(2-(4'-methyl-2,2'-bipyridin-4-yl)vinyl)benzene-1,3-diol of formula (2) with transition metal-(2,2'-bipyridine (bpy))2Cl2.2H2O complex in alcohol, followed by treatment with saturated aqueous ammonium hexafluorophosphate (NH4PF6) to precipitate the desired resorcinol bound transition metal-pyridyl complex as hexafluorophosphate salt of formulae (3) and (4); (iv) treating 5-(2-(4'-methyl-2,2'-bipyridin-4-yl)vinyl)benzene-1,3-diol of formula (2) with transition metal-pentacarbonyl chloride ((CO)5Cl) of rhenium (I) in presence of organic solvent to obtain tricarbonyl(5-(2-(4'-methyl-2,2'-bipyridin-4-yl)vinyl)benzene-1,3-diol)chlororhenium(I) of formula (8); and (v) optionally dissolving the ligand complexes of formula (I) in aqueous acetonitrile comprising water and acetonitrile in the ratio ranging between 95:5 and 99:1 (v/v), followed by adding the dissolved ligand complexes of formula I or formula II into 5-15 g/L aqueous colloidal solution of titanium dioxide (TiO2) nanoparticles having particle size of 2-5 nm with stirring to obtain resorcinol bound transition metal-pyridyl ligand complex of formula I covalently bound to TiO2. Preferred Components: The organic solvent used is polar aprotic solvent selected from tetrahydrofuran (THF), ethyl acetate, acetonitrile (ACN), dimethylformamide (DMF), dimethyl sulfoxide (DMSO) and its mixtures. The organic base used is selected from pyridine, diethylamine, triethylamine, and diisopropylethylamine. The alcohol is lower alcohol selected from methanol, ethanol, n-propanol, isopronol, butanol, isobutanol, tert.-butanol, pentanol or mixture of alcohol with polar aprotic solvent such as tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), dimethylformamide (DMF), and acetone. Preferred Process: Demethylation is carried out using molten pyridinium hydrochloride and not using boron tribromide in dichloromethane solvent. SPECIFIC COMPOUNDS - Specifically claimed are 3 resorcinol bound transition metal-pyridyl ligand complexes, e.g. tricarbonyl(5-(2-(4'-methyl-2,2'-bipyridin-4-yl)vinyl)benzene-1,3-diol)chlororhenium(I); (bis-(2,2'-bpy)-(5-(2-(4'-methyl-2,2'-bipyridin-4-yl)vinyl)benzene-1,3-diol)) hexafluoro phosphate; and (bis-(2,2'-bpy)-(5-(2-(4,-methyl-2,2'-bipyridin-4-yl)vinyl)benzene-1,3-diol))osmium(II) hexafluoro phosphate.    EXAMPLE - No suitable example given.