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Santos FDS, Ramasamy E, da Luz LC, Ramamurthy V, Rodembusch FS. Spectroscopic Insights of an Emissive Complex between 4'- N, N-Diethylaminoflavonol in Octa-Acid Deep-Cavity Cavitand and Rhodamine 6G. Molecules 2023; 28:molecules28114260. [PMID: 37298739 DOI: 10.3390/molecules28114260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 05/08/2023] [Accepted: 05/20/2023] [Indexed: 06/12/2023] Open
Abstract
Excited-state chemistry relies on the communication between molecules, making it a crucial aspect of the field. One important question that arises is whether intermolecular communication and its rate can be modified when a molecule is confined. To explore the interaction in such systems, we investigated the ground and excited states of 4'-N,N-diethylaminoflavonol (DEA3HF) in an octa acid-based (OA) confined medium and in ethanolic solution, both in the presence of Rhodamine 6G (R6G). Despite the observed spectral overlap between the flavonol emission and the R6G absorption, as well as the fluorescence quenching of the flavonol in the presence of R6G, the almost constant fluorescence lifetime at different amounts of R6G discards the presence of FRET in the studied systems. Steady-state and time-resolved fluorescence indicate the formation of an emissive complex between the proton transfer dye encapsulated within water-soluble supramolecular host octa acid (DEA3HF@(OA)2) and R6G. A similar result was observed between DEA3HF:R6G in ethanolic solution. The respective Stern-Volmer plots corroborate with these observations, suggesting a static quenching mechanism for both systems.
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Affiliation(s)
- Fabiano da Silveira Santos
- Grupo de Pesquisa em Fotoquímica Orgânica Aplicada, Instituto de Química, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, Bairro Agronomia, Porto Alegre CEP 91501-970, Brazil
| | - Elamparuthi Ramasamy
- Department of Chemistry and Biochemistry, The University of Texas at Arlington, Arlington, TX 76019, USA
| | - Lilian Camargo da Luz
- Grupo de Pesquisa em Fotoquímica Orgânica Aplicada, Instituto de Química, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, Bairro Agronomia, Porto Alegre CEP 91501-970, Brazil
| | | | - Fabiano Severo Rodembusch
- Grupo de Pesquisa em Fotoquímica Orgânica Aplicada, Instituto de Química, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, Bairro Agronomia, Porto Alegre CEP 91501-970, Brazil
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Ramamurthy V, Sen P, Elles CG. Ultrafast Excited State Dynamics of Spatially Confined Organic Molecules. J Phys Chem A 2022; 126:4681-4699. [PMID: 35786917 DOI: 10.1021/acs.jpca.2c03276] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
This Feature Article highlights the role of spatial confinement in controlling the fundamental behavior of molecules. Select examples illustrate the value of using space as a tool to control and understand excited-state dynamics through a combination of ultrafast spectroscopy and conventional steady-state methods. Molecules of interest were confined within a closed molecular capsule, derived from a cavitand known as octa acid (OA), whose internal void space is sufficient to accommodate molecules as long as tetracene and as wide as pyrene. The free space, i.e., the space that is left following the occupation of the guest within the host, is shown to play a significant role in altering the behavior of guest molecules in the excited state. The results reported here suggest that in addition to weak interactions that are commonly emphasized in supramolecular chemistry, the extent of empty space (i.e., the remaining void space within the capsule) is important in controlling the excited-state behavior of confined molecules on ultrafast time scales. For example, the role of free space in controlling the excited-state dynamics of guest molecules is highlighted by probing the cis-trans isomerization of stilbenes and azobenzenes within the OA capsule. Isomerization of both types of molecule are slowed when they are confined within a small space, with encapsulated azobenzenes taking a different reaction pathway compared to that in solution upon excitation to S2. In addition to steric constraints, confinement of reactive molecules in a small space helps to override the need for diffusion to bring the reactants together, thus enabling the measurement of processes that occur faster than the time scale for diffusion. The advantages of reducing free space and confining reactive molecules are illustrated by recording unprecedented excimer emission from anthracene and by measuring ultrafast electron transfer rates across the organic molecular wall. By monitoring the translational motion of anthracene pairs in a restricted space, it has been possible to document the pathway undertaken by excited anthracene from inception to the formation of the excimer on the excited-state surface. Similarly, ultrafast electron transfer experiments pursued here have established that the process is not hindered by a molecular wall. Apparently, the electron can cross the OA capsule wall provided the donor and acceptor are in close proximity. Measurements on the ultrafast time scale provide crucial insights for each of the examples presented here, emphasizing the value of both "space" and "time" in controlling and understanding the dynamics of excited molecules.
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Affiliation(s)
| | - Pratik Sen
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, UP 208 016, India
| | - Christopher G Elles
- Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, United States
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Petroselli M, Chen YQ, Rebek J, Yu Y. Binding and reactivity in deep cavitands based on resorcin[ ]arene. GREEN SYNTHESIS AND CATALYSIS 2021. [DOI: 10.1016/j.gresc.2021.03.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Samanta S, Baldridge A, Tolbert LM, Ramamurthy V. Guest/Host Complexes of Octa Acid and Amphiphilic Benzylidene-3-methylimidazolidinones Exchange Hosts within the NMR Time Scale. ACS OMEGA 2020; 5:8230-8241. [PMID: 32309733 PMCID: PMC7161058 DOI: 10.1021/acsomega.0c00523] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 03/19/2020] [Indexed: 06/11/2023]
Abstract
Cavitand octa acid (OA) is established to form a stable capsular assembly with one or two hydrophobic guest molecules (1:2 or 2:2 guest/host complex). Examples are known in which the guest molecule tumbles within the capsule without disrupting the structure of the capsuleplex. This process makes the two OA molecules that form the capsule magnetically equivalent. In this study, we have examined the dynamics of capsules that host amphiphilic benzylidene-3-methylimidazolidinone molecules as guests. In these capsuleplexes, although the guest does not tumble, the two OA molecules become magnetically equivalent because the two OA molecules that form the capsule exchange their positions in the NMR time scale. This is equivalent to the content of the capsule remaining stationary while the capsule swirls around it. Benzylidene-3-methylimidazolidinones form both 1:1 and 1:2 supramolecular complexes with cavitand OA. Two-dimensional NMR, ROESY, and NOESY data suggest that in a 300 ms time scale, the two halves of the capsule exchange between themselves and with free OA. The conclusion drawn here provides valuable information concerning the stability of the OA capsuleplex and cavitandplex that is used as the well-defined space to control the excited-state chemistry and dynamics of confined guest molecules.
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Affiliation(s)
- Shampa
R. Samanta
- Department
of Chemistry, University of Miami, Coral Gables, Miami, Florida 33146, United States
| | - Anthony Baldridge
- School
of Chemistry and Biochemistry, Georgia Institute
of Technology, 901 Atlantic Drive, Atlanta, Georgia 30332, United
States
| | - Laren M. Tolbert
- School
of Chemistry and Biochemistry, Georgia Institute
of Technology, 901 Atlantic Drive, Atlanta, Georgia 30332, United
States
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Wei X, Raj AM, Ji J, Wu W, Veerakanellore GB, Yang C, Ramamurthy V. Reversal of Regioselectivity during Photodimerization of 2-Anthracenecarboxylic Acid in a Water-Soluble Organic Cavitand. Org Lett 2019; 21:7868-7872. [DOI: 10.1021/acs.orglett.9b02860] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Xueqin Wei
- School of Pharmacy, Guangxi Medical University, Nanning 530021, China
- Key Laboratory of Green Chemistry & Technology of Ministry of Education, College of Chemistry, State Key Laboratory of Biotherapy, and Healthy Food Evaluation Research Center, Sichuan University, Chengdu 610064, China
| | - A. Mohan Raj
- Department of Chemistry, University of Miami, Coral Cables, Florida 33124, , United States
| | - Jiecheng Ji
- Key Laboratory of Green Chemistry & Technology of Ministry of Education, College of Chemistry, State Key Laboratory of Biotherapy, and Healthy Food Evaluation Research Center, Sichuan University, Chengdu 610064, China
| | - Wanhua Wu
- Key Laboratory of Green Chemistry & Technology of Ministry of Education, College of Chemistry, State Key Laboratory of Biotherapy, and Healthy Food Evaluation Research Center, Sichuan University, Chengdu 610064, China
| | | | - Cheng Yang
- Key Laboratory of Green Chemistry & Technology of Ministry of Education, College of Chemistry, State Key Laboratory of Biotherapy, and Healthy Food Evaluation Research Center, Sichuan University, Chengdu 610064, China
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Chuang CH, Porel M, Choudhury R, Burda C, Ramamurthy V. Ultrafast Electron Transfer across a Nanocapsular Wall: Coumarins as Donors, Viologen as Acceptor, and Octa Acid Capsule as the Mediator. J Phys Chem B 2017; 122:328-337. [DOI: 10.1021/acs.jpcb.7b11306] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Chi-Hung Chuang
- Center
for Chemical Dynamics and Nanomaterials Research, Department of Chemistry, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106, United States
| | - Mintu Porel
- Department
of Chemistry, University of Miami, Coral Gables, Florida 33124, United States
| | - Rajib Choudhury
- Department
of Physical Sciences, Arkansas Tech University, Russellville, Arkansas 72801, United States
| | - Clemens Burda
- Center
for Chemical Dynamics and Nanomaterials Research, Department of Chemistry, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106, United States
| | - V. Ramamurthy
- Department
of Chemistry, University of Miami, Coral Gables, Florida 33124, United States
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