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Wang Y, Chang JP, Xu R, Bai S, Wang D, Yang GP, Sun LY, Li P, Han YF. N-Heterocyclic carbenes and their precursors in functionalised porous materials. Chem Soc Rev 2021; 50:13559-13586. [PMID: 34783804 DOI: 10.1039/d1cs00296a] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Though N-heterocyclic carbenes (NHCs) have emerged as diverse and powerful discrete functional molecules in pharmaceutics, nanotechnology, and catalysis over decades, the heterogenization of NHCs and their precursors for broader applications in porous materials, like metal-organic frameworks (MOFs), porous coordination polymers (PCPs), covalent-organic frameworks (COFs), porous organic polymers (POPs), and porous organometallic cages (POMCs) was not extensively studied until the last ten years. By de novo or post-synthetic modification (PSM) methods, myriads of NHCs and their precursors containing building blocks were designed and integrated into MOFs, PCPs, COFs, POPs and POMCs to form various structures and porosities. Functionalisation with NHCs and their precursors significantly expands the scope of the potential applications of porous materials by tuning the pore surface chemical/physical properties, providing active sites for binding guest molecules and substrates and realizing recyclability. In this review, we summarise and discuss the recent progress on the synthetic methods, structural features, and promising applications of NHCs and their precursors in functionalised porous materials. At the end, a brief perspective on the encouraging future prospects and challenges in this contemporary field is presented. This review will serve as a guide for researchers to design and synthesize more novel porous materials functionalised with NHCs and their precursors.
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Affiliation(s)
- Yao Wang
- Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai 200438, P. R. China.
| | - Jin-Ping Chang
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, College of Chemistry and Materials Science, Northwest University, Xi'an 710127, P. R. China.
| | - Rui Xu
- Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai 200438, P. R. China.
| | - Sha Bai
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, College of Chemistry and Materials Science, Northwest University, Xi'an 710127, P. R. China.
| | - Dong Wang
- Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai 200438, P. R. China.
| | - Guo-Ping Yang
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, College of Chemistry and Materials Science, Northwest University, Xi'an 710127, P. R. China.
| | - Li-Ying Sun
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, College of Chemistry and Materials Science, Northwest University, Xi'an 710127, P. R. China.
| | - Peng Li
- Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai 200438, P. R. China.
| | - Ying-Feng Han
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, College of Chemistry and Materials Science, Northwest University, Xi'an 710127, P. R. China.
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Wang Y, Fu X, Liu S, Yang F, Wang J, Pan Y, Lu C, Xin T, Zhang T. A new gadolinium complex with 1, 3-bis (carboxymethyl) imidazolium chloride ionic liquid: Solvothermal synthesis, structure and magnetic properties. J Mol Struct 2020. [DOI: 10.1016/j.molstruc.2020.128340] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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3
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Jeoung S, Kim S, Kim M, Moon HR. Pore engineering of metal-organic frameworks with coordinating functionalities. Coord Chem Rev 2020. [DOI: 10.1016/j.ccr.2020.213377] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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4
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Yang P, Xiong G, He YK, You LX, Ren BY, Sun YG. Novel Zn and Cd Coordination Polymers Assembled from Imidazole-based Zwitterionic Ligands: Synthesis, Crystal Structures, and Luminescence Properties. RUSS J COORD CHEM+ 2019. [DOI: 10.1134/s1070328419100087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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5
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Kim H, Kim H, Kim K, Lee E. Structural Control of Metal–Organic Framework Bearing N-Heterocyclic Imidazolium Cation and Generation of Highly Stable Porous Structure. Inorg Chem 2019; 58:6619-6627. [DOI: 10.1021/acs.inorgchem.8b03173] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Hyunseok Kim
- Department of Chemistry, Pohang University of Science and Technology, Pohang, 790-784, Republic of Korea
| | - Hyunyong Kim
- Center for Self-assembly and Complexity, Institute for Basic Science (IBS), Pohang, 790-784, Republic of Korea
- Department of Chemistry, Pohang University of Science and Technology, Pohang, 790-784, Republic of Korea
| | - Kimoon Kim
- Center for Self-assembly and Complexity, Institute for Basic Science (IBS), Pohang, 790-784, Republic of Korea
- Department of Chemistry, Pohang University of Science and Technology, Pohang, 790-784, Republic of Korea
- Division of Advanced Materials Science, Pohang University of Science and Technology, Pohang, 790-784, Republic of Korea
| | - Eunsung Lee
- Center for Self-assembly and Complexity, Institute for Basic Science (IBS), Pohang, 790-784, Republic of Korea
- Department of Chemistry, Pohang University of Science and Technology, Pohang, 790-784, Republic of Korea
- Division of Advanced Materials Science, Pohang University of Science and Technology, Pohang, 790-784, Republic of Korea
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6
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Gan MM, Liu JQ, Zhang L, Wang YY, Hahn FE, Han YF. Preparation and Post-Assembly Modification of Metallosupramolecular Assemblies from Poly(N-Heterocyclic Carbene) Ligands. Chem Rev 2018; 118:9587-9641. [DOI: 10.1021/acs.chemrev.8b00119] [Citation(s) in RCA: 202] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ming-Ming Gan
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, College of Chemistry and Materials Science, Northwest University, Xi’an 710127, P. R. China
| | - Ji-Quan Liu
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, College of Chemistry and Materials Science, Northwest University, Xi’an 710127, P. R. China
| | - Le Zhang
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, College of Chemistry and Materials Science, Northwest University, Xi’an 710127, P. R. China
| | - Yao-Yu Wang
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, College of Chemistry and Materials Science, Northwest University, Xi’an 710127, P. R. China
| | - F. Ekkehardt Hahn
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, College of Chemistry and Materials Science, Northwest University, Xi’an 710127, P. R. China
- Institut für Anorganische und Analytische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 30, D-48149 Münster, Germany
| | - Ying-Feng Han
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, College of Chemistry and Materials Science, Northwest University, Xi’an 710127, P. R. China
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7
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Affiliation(s)
- Ganesan Prabusankar
- Department of Chemistry; Indian Institute of Technology Hyderabad; Kandi, Sangareddy, Telangana INDIA- 502 285
| | - Paladugu Suresh
- Department of Chemistry; Indian Institute of Technology Hyderabad; Kandi, Sangareddy, Telangana INDIA- 502 285
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8
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Nicasio AI, Montilla F, Álvarez E, Colodrero RP, Galindo A. Synthesis and structural characterization of homochiral 2D coordination polymers of zinc and copper with conformationally flexible ditopic imidazolium-based dicarboxylate ligands. Dalton Trans 2017; 46:471-482. [DOI: 10.1039/c6dt03712g] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Chiral imidazolium-based dicarboxylate ligands behave as bridging ditopic linkers capable of forming 2D coordination polymers with zinc and copper metals.
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Affiliation(s)
- Antonio I. Nicasio
- Departamento de Química Inorgánica
- Facultad de Química
- Universidad de Sevilla
- 41071 Sevilla
- Spain
| | - Francisco Montilla
- Departamento de Química Inorgánica
- Facultad de Química
- Universidad de Sevilla
- 41071 Sevilla
- Spain
| | - Eleuterio Álvarez
- Instituto de Investigaciones Químicas
- CSIC-Universidad de Sevilla
- 41092 Sevilla
- Spain
| | - Rosario P. Colodrero
- Departamento de Química Inorgánica
- Facultad de Química
- Universidad de Sevilla
- 41071 Sevilla
- Spain
| | - Agustín Galindo
- Departamento de Química Inorgánica
- Facultad de Química
- Universidad de Sevilla
- 41071 Sevilla
- Spain
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9
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Lee HJ, Kwon H, Sim J, Song D, Kim Y, Kim J, Kim K, Lee E. Synthetic control of coincidental formation of an N-heterocyclic carbene–copper(i) complex and imidazolium cations within metal–organic frameworks. CrystEngComm 2017. [DOI: 10.1039/c7ce00078b] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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10
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Raju G, Vishwanath S, Prasad A, Patel BK, Prabusankar G. Imidazolium tagged acridines: Synthesis, characterization and applications in DNA binding and anti-microbial activities. J Mol Struct 2016. [DOI: 10.1016/j.molstruc.2015.11.064] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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11
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Naga Babu C, Suresh P, Srinivas K, Sathyanarayana A, Sampath N, Prabusankar G. Catalytically active lead(ii)–imidazolium coordination assemblies with diversified lead(ii) coordination geometries. Dalton Trans 2016; 45:8164-73. [DOI: 10.1039/c5dt04409j] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Five new catalytically active lead(ii)–imidazolium coordination assemblies with diversified lead(ii) coordination geometries were successfully synthesized and used as catalysts for benzoin condensation reactions.
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Affiliation(s)
- Chatla Naga Babu
- Department of Chemistry
- Indian Institute of Technology Hyderabad
- Medak, India
| | - Paladugu Suresh
- Department of Chemistry
- Indian Institute of Technology Hyderabad
- Medak, India
| | - Katam Srinivas
- Department of Chemistry
- Indian Institute of Technology Hyderabad
- Medak, India
| | | | - Natarajan Sampath
- School of Chemical and Biotechnology
- SASTRA University
- Thanjavur, India
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12
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Ezugwu CI, Kabir NA, Yusubov M, Verpoort F. Metal–organic frameworks containing N-heterocyclic carbenes and their precursors. Coord Chem Rev 2016. [DOI: 10.1016/j.ccr.2015.06.012] [Citation(s) in RCA: 93] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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13
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Naga Babu C, Srinivas K, Prabusankar G. Facile access to zinc and cadmium selones: highly active catalysts for Barbier reactions in aqueous media. Dalton Trans 2016; 45:6456-65. [DOI: 10.1039/c5dt04871k] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Zinc and cadmium imidazoline selone complexes were synthesized and demonstrated to be potential catalysts for Barbier coupling in aqueous alcohol media.
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Affiliation(s)
- Chatla Naga Babu
- Department of Chemistry
- Indian Institute of Technology Hyderabad
- Medak
- 502 285 India
| | - Katam Srinivas
- Department of Chemistry
- Indian Institute of Technology Hyderabad
- Medak
- 502 285 India
| | - Ganesan Prabusankar
- Department of Chemistry
- Indian Institute of Technology Hyderabad
- Medak
- 502 285 India
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14
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Three luminescent d10 metal coordination polymers assembled from a semirigid V-shaped ligand with high selective detecting of Cu2+ ion and nitrobenzene. J SOLID STATE CHEM 2015. [DOI: 10.1016/j.jssc.2015.04.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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15
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Suresh P, Babu CN, Prabusankar G. A rare binuclear metallocyclic planar 20, 26 and 34 membered zinc-organic rings. Polyhedron 2015. [DOI: 10.1016/j.poly.2015.03.031] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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16
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Suresh D, Gomes CSB, Lopes PS, Figueira CA, Ferreira B, Gomes PT, Di Paolo RE, Maçanita AL, Duarte MT, Charas A, Morgado J, Vila-Viçosa D, Calhorda MJ. Luminescent Di- and Trinuclear Boron Complexes Based on Aromatic Iminopyrrolyl Spacer Ligands: Synthesis, Characterization, and Application in OLEDs. Chemistry 2015; 21:9133-49. [DOI: 10.1002/chem.201500109] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2015] [Indexed: 11/05/2022]
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17
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Sotnik SA, Polunin RA, Kiskin MA, Kirillov AM, Dorofeeva VN, Gavrilenko KS, Eremenko IL, Novotortsev VM, Kolotilov SV. Heterometallic Coordination Polymers Assembled from Trigonal Trinuclear Fe2Ni-Pivalate Blocks and Polypyridine Spacers: Topological Diversity, Sorption, and Catalytic Properties. Inorg Chem 2015; 54:5169-81. [DOI: 10.1021/ic503061z] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Svetlana A. Sotnik
- L. V. Pisarzhevskii Institute of Physical Chemistry of the National Academy of Sciences of the Ukraine, Prospekt Nauki 31, Kiev 03028, Ukraine
| | - Ruslan A. Polunin
- L. V. Pisarzhevskii Institute of Physical Chemistry of the National Academy of Sciences of the Ukraine, Prospekt Nauki 31, Kiev 03028, Ukraine
| | - Mikhail A. Kiskin
- N. S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Leninsky Prosp. 31, 119991 GSP-1 Moscow, Russian Federation
| | - Alexander M. Kirillov
- Centro de Química Estrutural, Complexo I, Instituto
Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon, Portugal
| | - Victoria N. Dorofeeva
- L. V. Pisarzhevskii Institute of Physical Chemistry of the National Academy of Sciences of the Ukraine, Prospekt Nauki 31, Kiev 03028, Ukraine
- Research-And-Education ChemBioCenter, National Taras Shevchenko University of Kyiv, Chervonotkackaya str., 61, Kiev 03022, Ukraine
| | - Konstantin S. Gavrilenko
- Research-And-Education ChemBioCenter, National Taras Shevchenko University of Kyiv, Chervonotkackaya str., 61, Kiev 03022, Ukraine
- Enamine Ltd., A. Matrosova
str. 23, Kiev 01103, Ukraine
| | - Igor L. Eremenko
- N. S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Leninsky Prosp. 31, 119991 GSP-1 Moscow, Russian Federation
| | - Vladimir M. Novotortsev
- N. S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Leninsky Prosp. 31, 119991 GSP-1 Moscow, Russian Federation
| | - Sergey V. Kolotilov
- L. V. Pisarzhevskii Institute of Physical Chemistry of the National Academy of Sciences of the Ukraine, Prospekt Nauki 31, Kiev 03028, Ukraine
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Suresh P, Babu CN, Prabusankar G. Semi-rigid imidazolium carboxylate controlled structural topologies in zwitterionic coordination networks. Polyhedron 2015. [DOI: 10.1016/j.poly.2014.12.039] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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19
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Suresh P, Naga Babu C, Sampath N, Prabusankar G. Photoluminescent calcium azolium carboxylates with diversified calcium coordination geometry and thermal stability. Dalton Trans 2015; 44:7338-46. [DOI: 10.1039/c5dt00480b] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Six new luminescent calcium coordination assemblies were successfully synthesized and characterized using bis- and tris-azolium carboxylic acid ligands.
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Affiliation(s)
- Paladugu Suresh
- Department of Chemistry
- Indian Institute of Technology Hyderabad
- ODF Campus
- Telangana 502 205, India
| | - Chatla Naga Babu
- Department of Chemistry
- Indian Institute of Technology Hyderabad
- ODF Campus
- Telangana 502 205, India
| | - Natarajan Sampath
- School of Chemical and Biotechnology
- SASTRA University
- Thanjavur, India
| | - Ganesan Prabusankar
- Department of Chemistry
- Indian Institute of Technology Hyderabad
- ODF Campus
- Telangana 502 205, India
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Figueira CA, Lopes PS, Gomes CSB, Veiros LF, Gomes PT. Exploring the influence of steric hindrance and electronic nature of substituents in the supramolecular arrangements of 5-(substituted phenyl)-2-formylpyrroles. CrystEngComm 2015. [DOI: 10.1039/c5ce00927h] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The supramolecular arrangements of 5-(substituted phenyl)-2-formylpyrroles display the core formation of dimers, tetramers or polymers, depending on the phenyl substituents.
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Affiliation(s)
- Cláudia A. Figueira
- Centro de Química Estrutural
- Departamento de Engenharia Química
- Instituto Superior Técnico
- Universidade de Lisboa
- 1049-001 Lisboa, Portugal
| | - Patrícia S. Lopes
- Centro de Química Estrutural
- Departamento de Engenharia Química
- Instituto Superior Técnico
- Universidade de Lisboa
- 1049-001 Lisboa, Portugal
| | - Clara S. B. Gomes
- Centro de Química Estrutural
- Departamento de Engenharia Química
- Instituto Superior Técnico
- Universidade de Lisboa
- 1049-001 Lisboa, Portugal
| | - Luís F. Veiros
- Centro de Química Estrutural
- Departamento de Engenharia Química
- Instituto Superior Técnico
- Universidade de Lisboa
- 1049-001 Lisboa, Portugal
| | - Pedro T. Gomes
- Centro de Química Estrutural
- Departamento de Engenharia Química
- Instituto Superior Técnico
- Universidade de Lisboa
- 1049-001 Lisboa, Portugal
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21
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Cationic zinc (II) dimers and one dimensional coordination polymer from ionic carboxylic acid. J CHEM SCI 2014. [DOI: 10.1007/s12039-014-0695-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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22
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Cadmium coordination polymers based on flexible bis(imidazole) ligands: A rare example for doublet of doublet cadmium polyhedron arrangements. J Mol Struct 2014. [DOI: 10.1016/j.molstruc.2014.06.074] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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23
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Kronstein M, Akbarzadeh J, Drechsel C, Peterlik H, Neouze MA. Tailoring Photoluminescence Properties in Ionic Nanoparticle Networks. Chemistry 2014; 20:10763-74. [DOI: 10.1002/chem.201400392] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2014] [Revised: 04/04/2014] [Indexed: 11/11/2022]
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24
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Suresh D, Lopes PS, Ferreira B, Figueira CA, Gomes CSB, Gomes PT, Di Paolo RE, Maçanita AL, Duarte MT, Charas A, Morgado J, Calhorda MJ. Tunable fluorophores based on 2-(N-arylimino)pyrrolyl chelates of diphenylboron: synthesis, structure, photophysical characterization, and application in OLEDs. Chemistry 2014; 20:4126-40. [PMID: 24634317 DOI: 10.1002/chem.201303607] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Indexed: 11/07/2022]
Abstract
Reactions of 2-(N-arylimino)pyrroles (HNC4H3C(H)=N-Ar) with triphenylboron (BPh3) in boiling toluene afford the respective highly emissive N,N'-boron chelate complexes, [BPh2 {κ(2)N,N'-NC4H3C(H)=N-Ar}] (Ar=C6H5 (12), 2,6-Me2-C6H3 (13), 2,6-iPr2-C6H3 (14), 4-OMe-C6H4 (15), 3,4-Me2-C6 H3 (16), 4-F-C6H4 (17), 4-NO2-C6H4 (18), 4-CN-C6H4 (19), 3,4,5-F3-C6H2 (20), and C6F5 (21)) in moderate to high yields. The photophysical properties of these new boron complexes largely depend on the substituents present on the aryl rings of their N-arylimino moieties. The complexes bearing electron-withdrawing aniline substituents 17-20 show more intense (e.g., ϕf =0.71 for Ar=4-CN-C6H4 (19) in THF), higher-energy (blue) fluorescent emission compared to those bearing electron-donating substituents, for which the emission is redshifted at the expense of lower quantum yields (ϕf=0.13 and 0.14 for Ar=4-OMe-C6H4 (15) and 3,4-Me2-C6H3 (16), respectively, in THF). The presence of substituents bulkier than a hydrogen atom at the 2,6-positions of the aryl groups strongly restricts rotation of this moiety towards coplanarity with the iminopyrrolyl ligand framework, inducing a shift in the emission to the violet region (λmax =410-465 nm) and a significant decrease in quantum yield (ϕf=0.005, 0.023, and 0.20 for Ar=2,6-Me2-C6H3 (13), 2,6-iPr2-C6H3 (14), and C6F5 (21), respectively, in THF), even when electron-withdrawing groups are also present. Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations have indicated that the excited singlet state has a planar aryliminopyrrolyl ligand, except when prevented by steric hindrance (ortho substituents). Calculated absorption maxima reproduce the experimental values, but the error is higher for the emission wavelengths. Organic light-emitting diodes (OLEDs) have been fabricated with the new boron complexes, with luminances of the order of 3000 cd m(-2) being achieved for a green-emitting device.
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Affiliation(s)
- D Suresh
- Centro de Química Estrutural, Departamento de Engenharia Química, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal)
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