A noncentrosymmetric (NCS) titanium-organic compound, [H2N(CH3)(2)] TiO{[NC5H3(CO2)(2)] [NC5H4(CO2)]} (CAUMOF-18), has been synthesized by a solvothermal reaction. The aligned unidimensional polar chain structure of CAUMOF-18 consisting of corner-shared distorted TiO5N2 pentagonal bipyramids is attributed to strong hydrogen-bonding and pi-pi interactions. CAUMOF-18 reveals a very strong second harmonic -generation efficiency of 400 times that of alpha-SiO2 and is phase-matchable (type I). Water-molecule driven reversible centricity conversion and topotactic transformation to TiO2 microrods for CAUMOF-18 are also presented.