This study reveals the tuning of the vibrational characteristics of the capping ligands in lanthanide [Ln = Sm, Eu, Tb, Dy] cation-incorporated zinc sulfide nanoparticles, Zn(Ln)S, as monitored by Fourier transform infrared (FTIR) spectroscopy. Both stearate and trioctylphosphine oxide (TOPO) were found to act as surface-capping ligands for nanoparticles with multiple coordination environments. The vibrational characteristics of the capping ligands in the undoped ZnS nanoparticles exhibited noticeable differences in absorption as compared to those of the pure zinc stearate and TOPO molecules. Lanthanide cation incorporation tunes the corresponding vibrational characteristics to a significant extent, as compared to that in the undoped ZnS nanoparticles. It has been argued that the observed tuning of the capping ligand IR absorption characteristics is induced by the lanthanide cations that are located near or on the surface of the nanoparticles. The IR spectra suggest a probable change of carboxylate coordination environment in the Zn(Ln)S nanoparticles. The results obtained from the ZnS-based nanoparticles were analyzed based on a semi-quantitative analysis and compared with those from ZnSe and Zn(Tb)Se nanoparticles, in order to evaluate the effect of the constituent anion of the nanoparticles in modulating the IR signature. © The Royal Society of Chemistry 2015.

PRASUN MUKHERJEE

GENERAL

A GHATAK

G H DEBNATH

M MANDAL

University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

RSC Advances

This work investigates the photoluminescence characteristics where cadmium selenide (CdSe) and zinc sulfide (ZnS) nanoparticles are treated post-synthetically by the trivalent lanthanide cations (Ln 3+ ) [Ln = Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb] separately to form either CdSe/Ln or ZnS/Ln nanoparticles. Host sensitized Ln 3+ emission was found to be present only in CdSe/Eu, CdSe/Tb, ZnS/Eu, ZnS/Tb and ZnS/Yb nanoparticles. In all the cases tuning of emission of the nanoparticles has been observed, irrespective of the presence or absence of host sensitization. The elemental compositions of CdSe and ZnS nanoparticles upon post-synthetic treatment show a remarkable difference. Incorporation of lanthanides in the nanoparticles is evident with significant alteration in the anionic content, and complete cation exchange of either Cd 2+ or Zn 2+ by Ln 3+ has not been detected; as evaluated from energy dispersive X-ray spectroscopy. Further evaluation on this comes from considering thermodynamic parameters of inter cation interaction. In cases where the host sensitized Ln 3+ emission have been observed, luminescence lifetime measurements reveal significant protection of Ln 3+ in the nanoparticles. Noticeable difference in photophysical properties for a given Ln 3+ has been realized in the two hosts. The photophysical observations have been rationalized using (i) charge trapping mediated host sensitized dopant emission, (ii) autoionization of excited electrons, and (iii) environment induced photoluminescence quenching. The post-synthetic modification discussed in the present work provides an easy and less synthetically demanding room temperature based protocol to avail lanthanide incorporated (doped) semiconductor nanoparticles that can potentially use the unique emission properties of the lanthanide cations. © 2019 Elsevier Inc.

Journal of Colloid and Interface Science

Host sensitized lanthanide photoluminescence from post-synthetically modified semiconductor nanoparticles depends on reactant identity

The spatial location of a foreign species (dopant) in a semiconductor nanoparticle matrix is probed by monitoring the infrared absorption and photoluminescence spectroscopy of the capping ligand and dopant moieties respectively at room temperature. The results have been rationalized within the domain of observables in each experiment and argued to provide a comprehensive picture in tracking the core and surface localized terbium cations that are incorporated in zinc sulfide nanoparticles. The progression of luminescence quantum yield of the core and surface localized terbium cations with doping extent induced variation has been found to be different. The generality of the experimental observations has been demonstrated with the corresponding europium incorporated nanoparticles. © 2016 The Royal Society of Chemistry.

Capping ligand infrared absorption and dopant photoluminescence spectroscopy provides a comprehensive picture to probe dopant spatial location in semiconductor nanoparticles

This work reports on the realization of luminescence from four visible emitting trivalent lanthanide (Ln) cations [samarium (Sm), europium (Eu), terbium (Tb) and dysprosium (Dy)] in polar zinc sulfide nanoparticles, Zn(Ln)S. Among the Zn(Ln)S nanoparticles studied, noticeable lanthanide cation centered luminescence has only been realized from the Zn(Tb)S and Zn(Eu)S nanoparticles in water, whereas no such effect has been observed in the corresponding Sm and Dy containing nanoparticles. In all the nanoparticles with characteristic lanthanide luminescence, the nanoparticles were found to be acting as an optical antenna and protector matrix, in order to realize luminescence from the respective lanthanide cations. The results have been rationalized with the lanthanide cations acting as charge (hole and/or electron) traps in the semiconductor nanoparticle matrix along with associated environmental effects. A comparison of the corresponding hydrophobic Zn(Tb)S nanoparticles reveal significant differences in photophysical properties. Finally, the hydrophilic Zn(Tb)S nanoparticles have been examined for in vitro cytotoxicity and the results indicate potential anti-cancer therapy for human mammary adenocarcinoma cells (MDA-MB-231) with the capability of cellular imaging. © The Royal Society of Chemistry 2016.

Towards the realization of luminescence from visible emitting trivalent lanthanides (Sm, Eu, Tb, Dy) in polar zinc sulfide nanoparticles: Evaluation of: In vitro cytotoxicity

The lanthanide photoluminescence in the trivalent terbium (Tb3+) incorporated zinc sulfide nanoparticles [Zn(Tb)S] has been reported with the nanoparticle size varying from 2.0 ± 0.3 to 14 ± 3 nm in diameter as a function of reaction temperature. In all the nanoparticles, the Tb3+ luminescence has been sensitized by the nanoparticle acting as an optical antenna. The relative contribution of different excitation bands in sensitizing Tb3+ luminescence in the Zn(Tb)S nanoparticles has been found to be dependent on the size of the nanoparticles. The observed Tb3+ luminescence efficiency in the Zn(Tb)S nanoparticles has been rationalized by competing factors: (i) the sensitization efficiency that is guided by the relative energy level position of the Tb3+ ground and excited states with respect to the valence and conduction bands of the ZnS and (ii) the extent of incorporation of Tb3+ in the nanoparticles. Additionally, it has been argued that the spectral overlap between the nanoparticle (donor) emission and Tb3+ (acceptor) absorption is not a prerequisite in determining the Tb3+ emission in the Zn(Tb)S nanoparticles studied. © 2015 American Chemical Society.

Journal of Physical Chemistry C

Controlled Terbium(III) Luminescence in Zinc Sulfide Nanoparticles: An Assessment of Competitive Photophysical Processes

We describe a novel method for creating luminescent lanthanide-containing nanoparticles in which the lanthanide cations are sensitized by the semiconductor nanoparticle's electronic excitation. In contrast to previous strategies, this new approach creates such materials by addition of external salt to a solution of fully formed nanoparticles. We demonstrate this postsynthetic modification for the lanthanide luminescence sensitization of two visible emitting lanthanides (Ln), Tb3+ and Eu3+ ions, through ZnS nanoparticles in which the cations were added postsynthetically as external Ln(NO3)3·xH2O salt to solutions of ZnS nanoparticles. The postsynthetically treated ZnS nanoparticle systems display Tb3+ and Eu3+ luminescence intensities that are comparable to those of doped Zn(Ln)S nanoparticles, which we reported previously (J. Phys. Chem. A, 2011, 115, 4031-4041). A comparison with the synthetically doped systems is used to contrast the spatial distribution of the lanthanide ions, bulk versus surface localized. The postsynthetic strategy described in this work is fundamentally different from the synthetic incorporation (doping) approach and offers a rapid and less synthetically demanding protocol for Tb3+:ZnS and Eu3+:ZnS luminophores, thereby facilitating their use in a broad range of applications. © 2013 American Chemical Society.

Journal	Data powered by TypesetRSC Advances
Publisher	Data powered by TypesetRoyal Society of Chemistry
ISSN	2046-2069
Open Access	No