TY  - JOUR
A1  - Kim, Jiyong
A1  - Kim, Yohan
A1  - Park, Kyoungwon
A1  - Boeffel, Christine
A1  - Choi, Hyung-Seok
A1  - Taubert, Andreas
A1  - Wedel, Armin
T1  - Ligand Effect in 1-Octanethiol Passivation of InP/ZnSe/ZnS Quantum Dots-Evidence of Incomplete Surface Passivation during Synthesis
JF  - Small : nano micro
N2  - The lack of anionic carboxylate ligands on the surface of InP/ZnSe/ZnS quantum dots (QDs), where zinc carboxylate ligands can be converted to carboxylic acid or carboxylate ligands via proton transfer by 1-octanethiol, is demonstrated. The as-synthesized QDs initially have an under-coordinated vacancy surface, which is passivated by solvent ligands such as ethanol and acetone. Upon exposure of 1-octanethiol to the QD surface, 1-octanethiol effectively induces the surface binding of anionic carboxylate ligands (derived from zinc carboxylate ligands) by proton transfer, which consequently exchanges ethanol and acetone ligands that bind on the incomplete QD surface. These systematic chemical analyses, such as thermogravimetric analysis-mass spectrometry and proton nuclear magnetic resonance spectroscopy, directly show the interplay of surface ligands, and it associates with QD light-emitting diodes (QD-LEDs). It is believed that this better understanding can lead to industrially feasible QD-LEDs.
KW  - colloidal quantum dots
KW  - incomplete surface passivation
KW  - indium
KW  - phosphide
KW  - surface chemistry
KW  - thiol passivation
Y1  - 2022
U6  - https://doi.org/10.1002/smll.202203093
SN  - 1613-6810
SN  - 1613-6829
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Goebel, Ronald
A1  - Hesemann, Peter
A1  - Friedrich, Alwin
A1  - Rothe, Regina
A1  - Schlaad, Helmut
A1  - Taubert, Andreas
T1  - Modular thiol-ene chemistry approach towards mesoporous silica monoliths with organically modified pore walls
JF  - Chemistry - a European journal
N2  - The surface modification of mesoporous silica monoliths through thiol-ene chemistry is reported. First, mesoporous silica monoliths with vinyl, allyl, and thiol groups were synthesized through a sol-gel hydrolysis-poly-condensation reaction from tetramethyl orthosilicate (TMOS) and vinyltriethoxysilane, allyltriethoxysilane, and (3-mercaptopropyl) trimethoxysilane, respectively. By variation of the molar ratio of the comonomers TMOS and functional silane, mesoporous silica objects containing different amounts of vinyl, allyl, and thiol groups were obtained. These intermediates can subsequently be derivatized through radical photoaddition reactions either with a thiol or an olefin, depending on the initial pore wall functionality, to yield silica monoliths with different pore-wall chemistries. Nitrogen sorption, small-angle X-ray scattering, solid-state NMR spectroscopy, elemental analysis, thermogravimetric analysis, and redox titration demonstrate that the synthetic pathway influences the morphology and pore characteristics of the resulting monoliths and also plays a significant role in the efficiency of functionalization. Moreover, the different reactivity of the vinyl and allyl groups on the pore wall affects the addition reaction, and hence, the degree of the pore-wall functionalization. This report demonstrates that thiol-ene photoaddition reactions are a versatile platform for the generation of a large variety of organically modified silica monoliths with different pore surfaces.
KW  - mesoporous materials
KW  - photochemistry
KW  - sol-gel processes
KW  - surface chemistry
Y1  - 2014
U6  - https://doi.org/10.1002/chem.201403982
SN  - 0947-6539
SN  - 1521-3765
VL  - 20
IS  - 52
SP  - 17579
EP  - 17589
PB  - Wiley-VCH
CY  - Weinheim
ER  -