A new series of panchromatic ruthenium(II) sensitizers derived from carboxylated terpyridyl complexes of tris-thiocyanato Ru(II) have been developed. The linkage isomers {(C 4 H 9 ) 4 N} 3 [Ru(Htcterpy)(-NCS) 3 ] 1, {(C 4 H 9 ) 4 N} 3 [Ru(Htcterpy)(-NCS) 2 (-SCN)] 2 and {(C 4 H 9 ) 4 N} 3 [[Ru(Htcterpy)(-SCN) 3 ] 3 have been separated by pH titration method and fully characterized by UV-Vis, emission, IR and NMR studies. The absorption and emission maxima of the isomer 1 show a bathochromic shift with decreasing pH, and exhibit pH-dependent excited state lifetimes. The red-shift of the emission maxima is due to better π-acceptor properties of the acid form that lowers the energy of the CT excited state. The isomer 1, when anchored to nanocrystalline TiO 2 films achieves very efficient sensitization over the whole visible range extending into the near IR region up to 920nm, yielding over 80% incident photon-to-current conversion efficiencies (IPCEs). Solar cells containing the isomer 1 were subjected to analysis by a photovoltaic calibration laboratory (NREL, USA) to determine their solar to electric conversion efficiency under standard AM 1.5 sunlight. A short circuit photocurrent density obtained was 20.5mA/cm 2 and the open circuit voltage was 0.72V corresponding to an overall conversion efficiency of 10.4%.