Surfactant-Free Synthesis and Functionalization of Highly Fluorescent Gold Quantum Dots

Abstract

A novel route has been developed for surfactant-free synthesis of highly fluorescent gold quantum dots (GQDs) in N,N-dimethylformamide (DMF). The as-prepared GQDs show instinctive fluorescence and good solubility in water. The formation mechanism and functionalization of GQDs were investigated by UV-vis spectra, fluorescence excitation and emission spectra, mass spectra, and TEM observation. Ligand-dependent optical properties of functionalized GQDs were found to be dramatically different. The approach provides a facile method of functionalization of bare GQDs for further applications, such as fluorescent biolabels, energy transfer units, and light-emitting devices.

A facile one-pot synthesis of blue and red luminescent thiol stabilized gold nanoclusters: a thorough optical and microscopy study

“…The bare AuNC were prepared according to the DMF reduction technique that was previously reported by Liu et al 25 In a typical procedure, 30 ml of N,N 0 -dimethylformamide (DMF) was poured into a three neck round-bottom flask under an argon atmosphere. The flask was then slowly heated in a silicon-oil bath and kept as such until the temperature reaches 145 1C.…”

“…11 Following this seminal work, various methods have been developed so far to synthesize monodisperse gold nanocluster of definite particle sizes by controlling the initial reaction conditions such as the thiol-to-gold ion ratio, reducing agents, temperature and also by modifying the post-synthesis purification processes. Several well defined nanoclusters have been synthesized so far such as Au 20 (SR) 16 , Au 25 (SR) 18 , Au 38 (SR) 24 , Au 102 (SR) 44 , and Au 144 (SR) 60 . [12][13][14][15][16][17] Among all these thiolate protected gold nanocluster, Au 25 (SR) 18 and Au 144 (SR) 60 are most widely studied due to their higher stability in comparison to other thiolated gold nanocluster.…”

“…Several well defined nanoclusters have been synthesized so far such as Au 20 (SR) 16 , Au 25 (SR) 18 , Au 38 (SR) 24 , Au 102 (SR) 44 , and Au 144 (SR) 60 . [12][13][14][15][16][17] Among all these thiolate protected gold nanocluster, Au 25 (SR) 18 and Au 144 (SR) 60 are most widely studied due to their higher stability in comparison to other thiolated gold nanocluster. The X-ray crystal structure of the Au 25 (SCH 2 CH 2 Ph) 18 nanocluster was also recently determined in both anionic and neutral forms.…”

“…These noble metal nanoparticles exhibit intense surface plasmon bands in the UV-Vis absorption spectrum. Later Liu et al 25 extended this idea of using DMF as both a reducing and stabilizing agent at high temperature and they have succeeded in developing a surfactant-free recipe to synthesize highly stable and luminescent gold nanocluster. Recently, Yabu et al 26 reported a novel one-pot process for the synthesis of AuNC via simple reduction of Au ions by amino-terminated poly(1,2-butadiene) (PB-NH 2 ) in toluene.…”

“…In this contribution we refer to a surfactant-free synthesis route by preparing highly stable and blue luminescent AuNC using N,N-dimethylformamide (DMF) as both a reducing and protecting agent, following the method originally proposed by Liu et al 25 with minor modifications. The as-synthesized bare AuNC were terminated with 1-dodecanethiol (1-DT).…”