title: Solvent-Switching Gelation and Orange-Red Emission of Ultrasmall Copper Nanoclusters.
abstract: By tuning the Cu⋅⋅⋅Cu and hydrogen-bonding interactions, the small cluster Cu3 L can be selectively synthesized to develop a stable and highly fluorescent material, as confirmed by matrix-assisted laser desorption ionization-time of flight mass spectroscopy. Further characterizations, including absorbance spectroscopy, XPS, and XRD demonstrate the formation of tiny Cu nanoclusters (NCs). In water, the as-prepared Cu NCs can exhibit high orange fluorescence via solution evaporation to eliminate hydrogen-bonding, and in dimethylformamide, a strong orange fluorescent gel is obtained by solvent induction to enhance the Cu⋅⋅⋅Cu and hydrogen-bonding interactions. More importantly, the Cu NCs in their substantial form exhibit nonlinear optical properties upon two-photon excitation. These results will shed light on Cu and related cluster applications in two-photon biological imaging, optical power limiting, and solar energy conversion.
authors.affiliation: Innovation Center for Advanced Materials, Nanjing Tech University, Nanjing, 211816, China. iamjhliu@njtech.edu.cn.|Department of Civil Engineering, University of HongKong, Porkfulam Road, HongKong, China. iamjhliu@njtech.edu.cn.
authors.forename: Jinhua
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Chemistry, University of Alberta, Edmonton, Alberta, T6G 2G2, Canada.
authors.forename: Qiang Matthew
authors.initials: QM
authors.lastname: Zhang
authors.affiliation: Department of Civil Engineering, University of HongKong, Porkfulam Road, HongKong, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Feng
authors.affiliation: Department of Civil Engineering, University of HongKong, Porkfulam Road, HongKong, China.
authors.forename: Zhengyuan
authors.initials: Z
authors.lastname: Zhou
authors.affiliation: Department of Civil Engineering, University of HongKong, Porkfulam Road, HongKong, China. kshih@hku.hk.
authors.forename: Kaimin
authors.initials: K
authors.lastname: Shih
mesh_terms: D003116:Color; D003300:Copper / Q000737:chemistry*; D005453:Fluorescence; D005782:Gels / Q000737:chemistry*; D006860:Hydrogen Bonding; D053768:Metal Nanoparticles / Q000737:chemistry*; D012993:Solar Energy; D012997:Solvents / Q000737:chemistry; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014867:Water / Q000737:chemistry
chemical_list: D005782:Gels; D012997:Solvents; D014867:Water; D003300:Copper
keywords: copper; gels; hydrogen bonds; nanoclusters; orange-red emission