Unexpected electronic perturbation effects of simple PEG environments on the optical properties of small cadmium chalcogenide clusters

Abstract

Poly(ethylene glycol) (PEG) has been widely used for the surface protection of inorganic nanoobjects because of its virtually 'inert' nature, but little attention has been paid to its inherent electronic impacts on inorganic cores. Herein, we definitively show, through studies on optical properties of a series of PEG-modified Cd(10)Se(4)(SR)(10) clusters, that the surrounding PEG environments can electronically affect the properties of the inorganic core. For the clusters with PEG units directly attached to an inorganic core (R = (CH(2)CH(2)O)nOCH(3), 1-PEGn, n = 3, ∼7, ∼17, ∼46), the absorption bands, associated with the low-energy transitions, continuously blue-shifted with the increasing PEG chain length. The chain length dependencies were also observed in the photoluminescence properties, particularly in the excitation spectral profiles. By combining the spectral features of several PEG17-modified clusters (2-C(m)-PEG17 and 3) whose PEG and core units are separated by various alkyl chain-based spacers, it was demonstrated that sufficiently long PEG units, including PEG17 and PEG46, cause electronic perturbations in the cluster properties when they are arranged near the inorganic core. These unique effects of the long-PEG environments could be correlated with their large dipole moments, suggesting that the polarity of the proximal chemical environment is critical when affecting the electronic properties of the inorganic cluster core.

Controlling the Interaction between Fluorescent Gold Nanoclusters and Biointerfaces for Rapid Discrimination of Fungal Pathogens

“…Meanwhile, the conformational arrangement of OEG may generate large dipole moments (Figure 4c), which can effectively perturb the electronic states of the proximal gold core and cause the blue shift of the absorption and emission peaks of Au−MUA/ OEG. 52 Moreover, we simply adjusted the OEG content via changing the [MUA]/[EDC]/[NHS] molar ratio. As shown in Figure S3, when the OEG content increased, the emission intensity of gold nanoclusters decreased.…”

“…The increased k nr of Au–MUA/OEG resulted in the shortened lifetime τ and the decreased QY. Meanwhile, the conformational arrangement of OEG may generate large dipole moments (Figure c), which can effectively perturb the electronic states of the proximal gold core and cause the blue shift of the absorption and emission peaks of Au–MUA/OEG . Moreover, we simply adjusted the OEG content via changing the [MUA]/[EDC]/[NHS] molar ratio.…”

Elucidating the role of surface passivating ligand structural parameters in hole wave function delocalization in semiconductor cluster molecules

“…This unique approach will lay the foundation for preparing artificial solids that have facile charge transport by lowering the inter-cluster tunneling barrier of ligand-passivated SCMs adhered to multilayer films, ultimately increasing the efficiency of solid-state devices. Furthermore, a strong electronic interaction at the SCM-ligand interface is expected to reduce the exciton tunneling barrier 36 and thus facilitate charge separation and extraction, which are critical for SCM photocatalytic applications. [21][22][23][24]…”