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61.
Jochen Jung Florian Benner Dr. Regine Herbst-Irmer Prof. Dr. Selvan Demir Prof. Dr. Dietmar Stalke 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(48):12310-12319
Lanthanide ions are particularly well-suited for the design of single-molecule magnets owing to their large unquenched orbital angular momentum and strong spin-orbit coupling that gives rise to high magnetic anisotropy. Such nanoscopic bar magnets can potentially revolutionize high-density information storage and processing technologies, if blocking temperatures can be increased substantially. Exploring non-classical ligand scaffolds with the aim to boost the barriers to spin-relaxation are prerequisite. Here, the synthesis, crystallographic and magnetic characterization of a series of each isomorphous mono- and dinuclear lanthanide (Ln=Gd, Tb, Dy, Ho, Er) complexes comprising tetraimido sulfate ligands are presented. The dinuclear Dy complex [{(thf)2Li(NtBu)2S(tBuN)2DyCl2}2 ⋅ ClLi(thf)2] ( 1c ) shows true signatures of single-molecule magnet behavior in the absence of a dc field. In addition, the mononuclear Dy and Tb complexes [{(thf)2Li(NtBu)2S(tBuN)2LnCl2(thf)2] ( 2b , c ) show slow magnetic relaxation under applied dc fields. 相似文献
62.
Gayathri Jayagopi Selvan Kumar Sangeetha Narayanan Sangilimuthu Sriman 《Journal of Solid State Electrochemistry》2018,22(9):2879-2888
Journal of Solid State Electrochemistry - In this work, the synthesised octadentate ligand immobilised multi-walled carbon nanotubes (MWCNTs) modified electrode as an electrochemical sensor of Hg2+... 相似文献
63.
Large Spin‐Relaxation Barriers for the Low‐Symmetry Organolanthanide Complexes [Cp*2Ln(BPh4)] (Cp*=pentamethylcyclopentadienyl; Ln=Tb,Dy)
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Dr. Selvan Demir Dr. Joseph M. Zadrozny Prof. Dr. Jeffrey R. Long 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(31):9524-9529
Single‐molecule magnets comprising one spin center represent a fundamental size limit for spin‐based information storage. Such an application hinges upon the realization of molecules possessing substantial barriers to spin inversion. Axially symmetric complexes of lanthanides hold the most promise for this due to their inherently high magnetic anisotropies and low tunneling probabilities. Herein, we demonstrate that strikingly large spin reversal barriers of 216 and 331 cm?1 can also be realized in low‐symmetry lanthanide tetraphenylborate complexes of the type [Cp*2Ln(BPh4)] (Cp*=pentamethylcyclopentadienyl; Ln=Tb ( 1 ) and Dy ( 2 )). The dysprosium congener showed hysteretic magnetization data up to 5.3 K. Further studies of the magnetic relaxation processes of 1 and 2 under applied dc fields and upon dilution within a matrix of [Cp*2Y(BPh4)] revealed considerable suppression of the tunneling pathway, emphasizing the strong influence of dipolar interactions on the low‐temperature magnetization dynamics in these systems. 相似文献
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65.
Prathibha T. Selvan B. Robert Venkatesan K. A. Rajeswari S. Antony M. P. 《Journal of Radioanalytical and Nuclear Chemistry》2017,311(3):1929-1935
Journal of Radioanalytical and Nuclear Chemistry - The radiation stability of N,N-di-alkyl-2-hydroxyacetamide derivatives having alkyl side chain varying from hexyl to decyl was studied as a... 相似文献
66.
Jammu Ravi B. Robert Selvan K. A. Venkatesan M. P. Antony T. G. Srinivasan P. R. Vasudeva Rao 《Journal of Radioanalytical and Nuclear Chemistry》2014,300(3):981-986
The radiolytic degradation of N,N-di-dodecyl-N′,N′-di-2-ethylhexyl-3-oxapentane-1,5-diamide (D3DEHDGA) was studied at various absorbed doses of γ-radiation. The degradation was assessed by measuring the variation in the extraction behavior of Am(III) in irradiated solvent systems composed of neat D3DEHDGA or 0.1 M D3DEHDGA/n-dodecane in the presence and absence of nitric acid. The distribution ratio of americium (D Am(III)) decreased with increase of absorbed dose. The presence of n-dodecane and nitric acid enhanced the radiolytic degradation of the solvent. The third phase formation behavior of Nd(III) decreased with increase of absorbed dose and the third phase was not observed at absorbed doses above 100 kGy. The recovery of Am(III) from the irradiated system was near quantitative in five contacts. The study revealed that the extraction and stripping behavior of the irradiated solvent was quite satisfactory for partitioning of minor actinides from real wastes. 相似文献
67.
Jammu Ravi B. Robert Selvan K. A. Venkatesan M. P. Antony T. G. Srinivasan P. R. Vasudeva Rao 《Journal of Radioanalytical and Nuclear Chemistry》2014,299(1):879-885
The radiation stability of N,N-di-dodecyl-N′,N′-di-octyl-3-oxapentane-1,5-diamide (D3DODGA) was studied by γ-irradiation of the solvent up to a absorbed dose of 1,000 kGy. The effect of γ-irradiation on the radiolytic degradation of D3DODGA was assessed by measuring the distribution ratio of Am(III) (D Am(III)) as well as the third phase formation in the irradiated D3DODGA-n-dodecane solution. The D Am(III) in the irradiated solution decreased with increase of absorbed dose. The critical aqueous concentration of Nd(III) above which the third phase forms, increased with increase of absorbed dose. However, the limiting organic concentration of Nd(III) remained at ~25 mM irrespective of the absorbed dose. Recovery of Am(III) from the radiolytically degraded organic phase showed that back extraction of Am(III) was quantitative in a few contacts using dilute nitric acid. Our studies clearly indicated that radiolytic degradation of D3DODGA in n-dodecane is marginal even at the absorbed dose of 1,000 kGy, and therefore D3DODGA is a potential candidate for minor actinide partitioning. 相似文献
68.
Pradip B. Dhamole Dhanashree Demanna S. A. Desai 《Applied biochemistry and biotechnology》2014,174(2):564-573
Ferulic acid (FA) and p-coumaric acid (pCA) are high-value products that can be obtained by alkaline hydrolysis of lignocellulose. Present work explores the potential of surfactant-based cloud-point extraction (CPE) for FA and pCA extraction from corn cob hydrolysate. More than 90 % (w/w) extraction of both FA and pCA was achieved from model system with L92. The partition coefficient of FA and pCA in L92 aqueous phase system was 35 and 55, respectively. A significant enrichment (8–10-fold) of both FA and pCA was achieved in surfactant-rich phase. Furthermore, the downstream process volume was reduced by 10 to 13 times. Optimized conditions (5 %?v/v?L92 and pH 3.0) resulted into 85 and 89 % extraction of FA and p-CA, respectively, from alkaline corn cob hydrolysate. Biocompatibility tests were carried out for L92 for ethanol fermentation and found to be biocompatible. Thus, the new surfactant-based CPE system not only concentrated FA and pCA but also reduced the process volume significantly. Further, aqueous phase containing sugars can be used for ethanol fermentation. 相似文献
69.
M. I. Oshtrakh M. V. Ushakov B. Senthilkumar R. Kalai Selvan C. Sanjeeviraja I. Felner V. A. Semionkin 《Hyperfine Interactions》2013,219(1-3):7-12
The nanocrystalline NiFe2O4 particles prepared by solution combustion synthesis technique using different fuels such as ethylene-diamine-tetra-acetic acid (NA sample) and urea (NB sample) were studied using magnetic measurement and 57Fe Mössbauer spectroscopy with a high velocity resolution. The temperature dependence of magnetization is different for the two samples. Mössbauer spectra demonstrate the necessity to use more than two magnetic sextets, usually used to fit the NiFe2O4 nanoparticles spectra. Evaluation of the different local microenvironments for Fe in both tetrahedral (A) and octahedral (B) sites, caused by different Ni2?+? occupation of octahedral sites, demonstrates at least five different local microenvironments for both A and B sites. Therefore, the Mössbauer spectra were fitted by using ten magnetic sextets which are related to the spread 57Fe location in octahedral and tetrahedral sites. 相似文献
70.
S. Arumugam M. Kanagaraj N. R. Tamil Selvan S. Esakki Muthu J. Prakash G. S. Thakur A. K. Ganguli H. Yoshino K. Murata K. Matsubayashi Y. Uwatoko 《固体物理学:研究快报》2012,6(5):220-222
The Effect of pressure on the superconducting transition temperature of Yb doped Ce0.6Yb0.4FeAsO0.9F0.1 has been investigated for the first time using resistivity and magnetization studies. Increase in chemical pressure by substitution of smaller Yb3+ ions in place of Ce3+ ions results in a significant enhancement of Tc from 38 K (Yb free) to 47 K (40% Yb). Enhancement in Tc with external pressure has been observed for this compound up to a maximum value of Tc = 48.7 K at 1 GPa, beyond which Tc starts decreasing monotonously. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献