A new conspicuous absorption peak at 425 nm(e = 5418 mol1Lcm1) and weak broad absorption at 475 nm(e = 1460 mol
1Lcm1) were observed in the Cu(II) complex,which could be assigned to 2 B1g ?2 A1g and 2 B1g ?2 B2g transitions
of distorted square pyramidal geometry of the Cu(II) complex [39].These observations were in line with common spectral features of d-block metal complexes. The absorption edge (kedge)of HL1 was at 412 nm, corresponding to an optical band gap (Eopt) of 3.010 eV.The absorption edge (kedge) of the Cu(II) complex was determined to be 526 nm yielding an optical band gap (Egopt) of 2.357 eV. With the increase of conjugated system, the band gap became narrower from the ligand HL1 to the Cu(II) complex