Fig. 4. (a) UV-vis spectra of AuNP2 (red), AuNP5 (green), AuNP9 (blue) and AuNP12 (dark yellow). Inset shows the corresponding photograph of the NPs under visible light. (b) UV-vis spectra of the Au(i)–SG complex. (c) Photoluminescence spectra of AuNP2 (red), AuNP5 (green), AuNP9 (blue) and AuNP12 (dark yellow). Excitation wavelength (λex) was at 409 nm. Inset shows the photographs of the NPs under UV light. (d) DLS spectra of Au(i)–SG complexes at pH 2 (red), 5 (green), 9 (blue) and 12 (dark yellow). The dotted arrow indicates the reduction of complex size with different pH. (e–h) Simplified core-in-cage structure model shows the presence and absence of intramolecular aurophilic interaction in different AuNPs.
