Silver(I)-directed growth of metal-organic complex nanocrystals with bidentate ligands of hydroquinine anthraquinone-1,4-diyl diethers as linkers at the water-chloroform interface

Immiscible liquid-liquid interfaces provide unique double phase regions for the design and construction of nanoscale materials. Here, we reported Ag(I)-directed growth of metal-organic complex nanocrystals by using AgNO₃ as a connector in the aqueous solution and bidentate ligand of 1,4-bis(9-O-dihydroquininyl)anthraquinone [(DHQ)₂AQN] and its enantiomer of (DHQD)₂AQN in the chloroform solutions as linkers. The Ag-(DHQ)₂AQN and Ag-(DHQD)₂AQN complex nanocrystals were formed at the liquid-liquid interfaces and characterized by using UV-vis absorption and fluorescence spectroscopy and X-ray photoelectron spectroscopy, as well as by using scanning electron microscopy. Screw-like nanocrystals were formed at the initial 30 min after the interfacial coordination reaction started, then they grew into nanorods after several days, and finally became cubic microcrystals after 2 weeks. The pure ligand showed two emission bands centered at about 363 and 522 nm in the methanol solution, the second one of which was quenched and shifted to about 470 nm in the Ag-complex nanocrystals. Two couples of reversible redox waves were recorded for the Ag-complex nanocrystals; one centered at about -0.25 V (vs. Ag/AgCl) was designated to one electron transfer process of Ag - (DHQ)₂AQN and Ag - (DHQ)₂AQN⁺, and the other one centered at about 0.2 V was designated to one electron transfer process of Ag - (DHQ)₂AQN and Ag⁺ - (DHQ)₂AQN.