AbstractIn this context we have synthesised and characterised a novel heteroleptic [Ru (4′‐(4 N,N dimethyl phenyl) 2,2′6’:2′′‐terpyridine) 4′‐(4Carboxyphenyl)‐2,2′6’:2′′‐terpyridine]2PF6 complex [PR2] with prolonged excited‐state lifetime τ of6.37 ns which is 25 fold more than the homologous [Ru(tpy)2](PF6)2. The appropriate selection of ligand moieties is employed for engineering the energy level of3MLCTand 3MC excited states to restrain the nonradiativeemissionfromthermally populated 3MC excited state.This task is well judged by counter balancing effect ofStrong σ‐ donor and π‐ acceptor substituent attached to terpyridyl moiety. This title complex exhibits an oxidation potential (E1/2) of 1.28 V vs Ag/AgCl. Thetime‐resolved absorption spectroscopy employed for interfacial charge transfer study reveals strong coupling in title complex–semiconducting TiO2 nanoparticle system which facilitates pulse width limited (<100 fs) ultrafast single exponential electron injection.