Highly stable 7-N,N-dibutylamino-2-azaphenanthrene and 8-N,N-dibutylamino-2-azachrysene as a new class of second order NLO-active chromophores

7-N,N-Dibutylamino-2-azaphenanthrene (L(3)), 8-N,N-dibutylamino-2-azachrysene (L(4)) and related Ir(I) complexes or alkylated salts show high second-order NLO responses, as determined by the EFISH technique and DFT calculations. L(4) is appealing as building block for NLO active materials due to its unexpected large mu beta(1.907)value and its very high thermal stability.