Structural Variation and Luminescence Properties of Tri- and Dinuclear Cu^II and Zn^II Complexes Constructed from a Naphthalenediol-Based Bis(Salamo)-type Ligand

Abstract

Three trinuclear complexes constructed from a naphthalenediol-based bis­(Salamo)-type tetraoxime ligand (H4L1), [Cu3(L1)­(OAc)2]­·CH3OH (1), [Zn3(L1)­(OAc)2­(CH3OH)2]­·4CHCl3 (2), and [Cu2(L1)­Na­(NO3)­(CH3OH)] (3), and one dinuclear complex, [{Cu­(L2)}2] (4), based on an unexpected ligand H2L2 derived from the cleavage of H4L1 have been synthesized and characterized by X-ray diffraction analyses. Different anionic sources, transition metal salts, and rationally controlled reaction conditions play important roles in the construction of the resulting complexes with variable coordination geometries (coordination number ranges from 4 to 7), and four types of supramolecular network were controlled by noncovalent interactions, such as hydrogen bond, π···π stacking, C–H···π, Cu···π, and halogen-related interactions. The fluorescence properties of H4L1 and its complexes were investigated, and 2 exhibits unique bright cyan–yellow visible fluorescent emissions in different solvents.

Tri- and Mono-Nuclear Zinc(II) Complexes Based on Half- and Mono-Salamo Chelating Ligands

“…Complex 1 includes one Zn(II) ion, one completely deprotonated (L 1 ) 2− unit and one coordinated ethanol molecule, which shows a slightly distorted As we know, many fluorescent complexes, especially those containing polar substituents on aromatic rings, are susceptible to solvents [27]. Due to the difference in polarity of solvents, complex 1 exhibits the relatively strong maximum fluorescence emission with relatively low solvent polarity in TCM and DCM at 439 and 440 nm, respectively.…”

“…The first part was linked by intermolecular N2-H2B···O9, N4-H4B···O16 and C29-H29···O15 [41,64] hydrogen bonding interactions. The other part was made up of the C-Cl···π [27], C-H···π stacking interactions. The Cg7 (C 15 -C 20 ) and Cg6 (C 1 -C 6 ) of phenyl rings as acceptors form two hydrogen bonds with the protons (-C29Cl2 and -C10H10B) of adjacent molecules.…”

“…The Cg7 (C15-C20) and Cg6 (C1-C6) of phenyl rings as acceptors form two hydrogen bonds with the protons (-C29Cl2 and -C10H10B) of adjacent molecules. The intermolecular hydrogen bonds and C-Cl···π, C-H···π stacking interactions of complex 2 not only make its spatial structure more diversified, but also may cause better chemical stability [27,59].…”

“…Furthermore, the maximum fluorescence emission unusually appears at 373 nm in MeOH solvent. The influence of the solvent effect changes the luminescent properties of complexes 1 and 2, making its application areas broad [27,69]. …”

“…As we know, Salen-type ligands (R-CH=N-(CH 2 ) 2 -N=CH-R) and their metal complexes have been extensively investigated in modern coordination chemistry for several decades [1][2][3][4][5], which have been extensively investigated in potential application in biological fields [6][7][8][9][10][11][12][13], electrochemical conducts [14,15], nonlinear optical materials [16][17][18][19][20], magnetic materials [21][22][23][24][25], luminescence properties [26][27][28][29][30][31][32], and supramolecular architecture [33][34][35][36][37], and so on. Chemical modifications of substituent or functional groups in the Salen N 2 O 2 ligands are effective in exchanging the structures or the main functions of complexes, such as salamo ligand, a Salen analogue, (R-CH=N-O-(CH) n -O-N=CH-R) is one of the most versatile ligands and the large electronegativity of oxygen atoms is expected to strongly affect the electronic properties of the N 2 O 2 coordination sphere, which can lead to different and novel structures and properties of the resulting complexes [38].…”