Upconversion nanoparticles (β-NaYF4:Er3+, Yb3+, UCNPs) were capped with a thin polymer shell by replacing the oleate ligand of hydrophobic UCNPs by multidentate thiolate-grafting of P(MEO2MA-co-SEMA) copolymers. The presence of the 2-(2-methoxyethoxy)ethyl side chains of MEO2MA extending out of the nanohybrid made them water-dispersible. The UCNP@P(MEO2MA-co-SEMA) nanohybrids exhibited an enhanced emission by up to a factor of 10, as compared with that of their hydrophobic precursor in dichloromethane and even in water (a factor of 2). Moreover, their thermoresponsiveness was modulated by the pH; this is consistent with the presence of some thiol groups at the nanohybrid periphery. Remarkably, the nanohybrid emission, as well as its stability, was almost independent of the aggregation state (in the basic-acid and temperature range studied here). The formation of stable water-dispersible UCNPs with enhanced emission, together with their amphiphilic and temperature-responsive polymer coating, is promising for building multifunctional nanostructures for intracellular imaging, therapy, and drug delivery.
The five-coordinate complexes MHCl(CO)(PiPr3)2 (M = Os (1), Ru (2)) react with NaSH to give the unsaturated hydrido−metallothiol derivatives MH(SH)(CO)(PiPr3)2 (M = Os (3), Ru (4)). Complexes 3 and 4 react with CO to afford the cis-dicarbonyl compounds MH(SH)(CO)2(PiPr3)2 (M = Os (5), Ru (6)). Similarly, the reaction of 3 with P(OMe)3 leads to OsH(SH)(CO){P(OMe)3}(PiPr3)2 (7). Treatment of 3 with 1 equiv of acetylenedicarboxylic methyl ester which is the result of the trans addition of the S−H bond of 3 to the carbon−carbon triple bond of the alkyne. The structure of 8 was determined by X-ray investigation. The geometry of the complex can be rationalized as a distorted octahedron with the two phosphorus atoms of the triisopropylphosphine ligands occupying apical positions. The equatorial plane is formed by the bidentate ligand, which acts with a bite angle of 89.49(12)°, the hydrido ligand trans-disposed to the oxygen atom, and the carbonyl group trans-disposed to the sulfur atom. Acetylenedicarboxylic methyl ester also reacts with 4 by insertion of the carbon−carbon triple bond into the S−H bond. However, in the resulting monothio-β-diketonato the hydrido ligand lies trans to the sulfur atom. In solution, complex 9 isomerizes into 10, containing the hydrido ligand trans-disposed to the oxygen atom of the chelate group. The stereochemistry of 10 was corroborated by X-ray investigation. The geometry of 10 is the same as that of 8, and the structural parameters of both molecules are statistically identical. Phenylacetylene and methylpropiolate, in contrast to acetylenedicarboxylic methyl ester, react with 3 and 4 by insertion of the carbon−carbon triple bonds into the M−H bonds to give the unsaturated alkenyl−metallothiol complexes M{(E)-CHCHPh}(SH)(CO)(PiPr3)2 (M = Os (11), Ru (12)) and Ru{(E)-CHCHCO2CH3}(SH)(CO)(PiPr3)2 (13).
Well‐defined thermoresponsive polymers obtained by the atom transfer radical polymerization (ATRP) of short oligo(ethylene glycol) methyl ether methacrylates (MEOnMA, n = 2, 3, or 8) with small ratios of a thiolated comonomer, 2‐(acetylthio)ethylmethacrytale, can replace the hydrophobic trioctylphosphine oxide (TOPO) capping of CdSe quantum dots (QDs). After this facile ligand exchange, the mild hydrolysis of the acetylthiol group into thiol is the key to enhance the QD luminescence. However, the length of the ethylene glycol side chain is critical for the success of the functionalization; it is established that the shortest MEO2MA‐based copolymers result in a compact coating and a highest quantum yield (up to a factor of 6) when compared with that of CdSe@TOPO in dichloromethane. In addition, the amphiphilic character of the copolymer allows the CdSe@P(MEOnMA‐co‐SEMA) nanohybrids to disperse in water. On the other hand, the residual ionizable thiol groups do not get attached to the QD surface, cause that the lower critical solubility temperature of the polymer depends on pH as well. Thus, at acidic pH, an abrupt increase in the luminescence emission accompanies the polymer collapse, which establishes the promise of these hybrids as temperature/pH nanosensors and targeted drug delivery. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 3087–3095
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.