NDLI: Complexation of Eu(III) with Cucurbit[n]uril, n = 5 and 7: A Thermodynamic and Structural Study

Content Provider	World Health Organization (WHO)-Global Index Medicus
Author	Jha, S. N. Kar, Aishwarya Bhattacharyya, D. Nayak, C. Bhattacharyya, A. Tomar, B. S. Rawat, Neetika Nayak, S. K. Rao, Ankita
Description	Author Affiliation: Rawat N ( Radioanalytical Chemistry Division, Bhabha Atomic Research Centre, Mumbai - 4000 085, India. neetika@barc.gov.in.)
Abstract	Cucurbit[n]urils (CBn) are a new class of macrocyclic cage compounds capable of binding organic and inorganic species, owing to their unique pumpkin like structure comprising of both a hydrophobic cavity and a hydrophilic portal. The thermodynamics of the complexation of Eu(III) with CBn of a different cavity size viz. cucurbit[5]uril (CB5) and cucurbit[7]uril (CB7) has been studied by UV-Vis spectroscopy and calorimetry at 25 °C whereas the structure of the complexes was investigated using time resolved fluorescence spectroscopy (TRFS) and extended X-ray absorption fine structure spectroscopy (EXAFS) in a formic acid–water mixture (50 wt%). This is the first report on the structural investigation of Eu–CBn complexes in solution. The thermodynamic data (ΔG, ΔH and ΔS) for Eu(III) complexation with CBn reveal the formation of a 1:1 complex with CB5, while both 1:1 and 1:2 complexes are observed with CB7. The signatures of these species are observed in ESI-MS measurements, which corroborates with the species postulated in thermodynamic studies. The complexation reactions are found to be driven by ΔS as ΔH is either small negative or positive indicating the formation of inner sphere complexes, which is in line with TRFS and EXAFS results. These studies show that Eu(III) caps one of the CB5 portals by binding with all the carbonyl groups in the 1:1 Eu–CB5 complex, whereas in the 1:1 Eu–CB7 complex, Eu(III) interacts with only a few of the carbonyl groups of CB7. The computational studies (DFT calculations) on Eu–CB5 and Eu–CB7 complexes further support the experimental data.
ISSN	14779226
Issue Number	9
Volume Number	44
e-ISSN	13645447
Journal	Dalton Trans.
Language	English
Publisher	Royal Society of Chemistry
Publisher Date	2015-03-07
Publisher Place	Great Britain (UK)
Access Restriction	Subscribed
Subject Keyword	Bridged Compounds Chemistry Coordination Complexes Europium Imidazoles Molecular Conformation Spectrum Analysis Methods Thermodynamics Journal Article
Content Type	Text
Resource Type	Article
Subject	Inorganic Chemistry

Sl.	Authority	Responsibilities	Communication Details
1	Ministry of Education (GoI), Department of Higher Education	Sanctioning Authority	https://www.education.gov.in/ict-initiatives
2	Indian Institute of Technology Kharagpur	Host Institute of the Project: The host institute of the project is responsible for providing infrastructure support and hosting the project	https://www.iitkgp.ac.in
3	National Digital Library of India Office, Indian Institute of Technology Kharagpur	The administrative and infrastructural headquarters of the project	Dr. B. Sutradhar bsutra@ndl.gov.in
4	Project PI / Joint PI	Principal Investigator and Joint Principal Investigators of the project	Dr. B. Sutradhar bsutra@ndl.gov.in Prof. Saswat Chakrabarti will be added soon
5	Website/Portal (Helpdesk)	Queries regarding NDLI and its services	support@ndl.gov.in
6	Contents and Copyright Issues	Queries related to content curation and copyright issues	content@ndl.gov.in
7	National Digital Library of India Club (NDLI Club)	Queries related to NDLI Club formation, support, user awareness program, seminar/symposium, collaboration, social media, promotion, and outreach	clubsupport@ndl.gov.in
8	Digital Preservation Centre (DPC)	Assistance with digitizing and archiving copyright-free printed books	dpc@ndl.gov.in
9	IDR Setup or Support	Queries related to establishment and support of Institutional Digital Repository (IDR) and IDR workshops	idr@ndl.gov.in