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Recent Progress of Squaraine-Based Fluorescent Materials and Their Biomedical Applications. Symmetry (Basel) 2022. [DOI: 10.3390/sym14050966] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Squaraines (SQs) are unusual cyanine dyes with a unique resonance-stabilized zwitterionic structure. These dyes have attracted significant attention in the fields of organic electronics and organic photonics, due to their facile synthesis, intense and narrow visible and near-infrared absorption/emission, high photostability, low biotoxicity, etc. In this review, we summarize the recent progress of SQ-based fluorescent materials and their biomedical applications. After a brief introduction to SQs, general synthetic routes and design principles of SQ-based fluorescent materials, as well as their aggregation-induced luminescence behaviors, are discussed. Subsequently, their biomedical applications for cell imaging and as fluorescent sensors and therapeutic agents are introduced. Finally, a summary and perspective are given for promoting the development of SQs-based fluorescent materials.
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Sawada R, Maeda T, Oda Y, Yagi S, Karunakaran V, Fujiwara H, Ajayaghosh A. Synthesis, Photophysical and Electrochemical Properties of Bis-Squaraine Dyes Fused on Isomeric Benzodipyrrole Central Units. Chem Asian J 2022; 17:e202200227. [PMID: 35333439 DOI: 10.1002/asia.202200227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Revised: 03/25/2022] [Indexed: 11/10/2022]
Abstract
Exciton interactions are not only observed in assembled molecules but also in compounds with multiple chromophores referred to as superchromophores. We have developed isomeric bis-squaraine dyes as superchromophores in which two squaraine chromophores are fused onto the isomeric benzodipyrrole skeleton so as to regulate conformations and to reduce distances between two chromophores. The dyes with benzo[1,2-b:3,4-b']dipyrrole and benzo[1,2-b:5,4-b']dipyrrole moieties exhibited split electronic absorption originated from the intramolecular exciton interaction. The intensity of the split absorption bands varies in correlation with the orientation of chromophores. The isomeric dye with benzo[1,2-b:4,5-b']dipyrrole moiety exhibited a near-infrared absorption associated with the resonance throughout two chromophores. Their electrochemical and spectroelectrochemical properties are distinct from those of monomeric dyes owing to electronic interactions between the two chromophores. Thus, the structural isomerism of the central skeleton significantly affects their optical properties as well as their electrochemical properties.
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Affiliation(s)
- Ryuhei Sawada
- Graduate School of Engineering, Osaka Prefecture University, Department of Applied Chemistry, Gakuen-cho, 599-8531, Sakai, JAPAN
| | - Takeshi Maeda
- Osaka Prefecture Univesity, Department of Applied Chemistry, Gakuen-cho, 599-8531, Sakai, JAPAN
| | - Yuya Oda
- Graduate School of Engineering, Department of Applied Chemistry, JAPAN
| | - Shigeyuki Yagi
- Graduate School of Engineering, Department of Applied Chemistry, Gakuen-cho, 599-8531, Sakai, JAPAN
| | - Venugopal Karunakaran
- NIIST-CSIR: National Institute for Interdisciplinary Science and Technology CSIR, Photosciences and Photonics Section, Chemical Sciences and Technology Division, 695 019, Thiruvananthapuram, INDIA
| | - Hideki Fujiwara
- Graduate School of Science, Department of Chemistry, Gakuen-cho, 599-8531, Sakai, JAPAN
| | - Ayyappanpillai Ajayaghosh
- NIIST-CSIR: National Institute for Interdisciplinary Science and Technology CSIR, Chemical Sciences and Technology Division, 695 019, Thiruvananthapuram, INDIA
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