Isomer Restriction on a Nanoparticle Surface and Enhanced Blue Emission

• Published in: Journal of the American Chemical Society Vol. 131; no. 5; pp. 1648 - 1649
• Main Authors: Cai, Xichen, Adhikari, Ravi M, Anyaogu, Kelechi C, Palayangoda, Sujeewa S, Estrada, Leandro A, De, Puran K, Neckers, Douglas C
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 11.02.2009
• Subjects: Copper - chemistry; Gold - chemistry; Isomerism; Magnetic Resonance Spectroscopy; Metal Nanoparticles - chemistry; Models, Molecular; Photochemical Processes; Silver - chemistry; Spectrophotometry, Ultraviolet; Sulfhydryl Compounds - chemistry; Surface Properties; Thermodynamics; Thiophenes - chemistry
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja807511f

5-Mercapto-2,2′-bithiophene (BTSH) functionalized copper (Cu), silver (Ag), and gold (Au) nanoparticles (NPs) of various diameters have been synthesized. Emission with a peak around 455 nm is detected on irradiation with UV light. This emission, however, disappears upon photopolymerization of the NPs. The photophysical study of BTSH at room and low temperatures indicates that the trans-isomer should be dominant when attached onto the surface of an NP. The electronic interaction among the ligands and NP core likely restricts the isomerization of BTSH and forms an emissive excited state. Therefore, we suggest that the trans isomer assembles on the NP surface giving the enhanced blue emission. As a control, no such isomer restriction in the case of 5-(5-mercaptopentyl)-2,2′-bithiophene (BTC5SH) is observed when attached on the NP surface.