Excimer formation and dual fluorescence emission of a hydroxyquinoline based macrocyclic tripod: existence of intra and intermolecular π-stacking

RSC Advances ◽  
2016 ◽  
Vol 6 (109) ◽  
pp. 108017-108027 ◽  
Author(s):  
Rohini Rohini ◽  
Minati Baral ◽  
B. K. Kanungo

The excited state reaction of 1,4,7-tris-(5-methylene-8-hydroxyquinoline)-1,4,7-triazacyclononane was studied in solution. The intramolecular-π-stacked tripod shows pH-dependent eximer emission and dual fluorescence due to intermolecular π-stacking.

Author(s):  
Zhe Tang ◽  
Haiyun Han ◽  
Junxia Ding ◽  
PanWang Zhou

As a special fluorescence phenomenon, double fluorescence has been widely developed and applied in various fields. Nevertheless, most of the research of fluorescence emission channel stay in the first excited...


1990 ◽  
Vol 55 (8) ◽  
pp. 1891-1895 ◽  
Author(s):  
Peter Ertl

Twisting of the NMe2 group in p-N,N-dimethylaminobenzonitrile (DMABN) was investigated using AM1 semiempirical method with configuration interaction. Effect of polar media was considered by placing + and - charge centers ("sparkles") at appropriate places opposite the molecule. Optimized ground state geometry of DMABN is slightly twisted with the lowest vertical excited state of 1B character. As the polarity of media increases and/or the - NMe2 group twists, the symmetric 1A excited state having considerable charge separation becomes energetically favorable. Anomalous long-wavelength emission of DMABN comes from this state.


Author(s):  
Sergey A. Bagnich ◽  
Alexander Rudnick ◽  
Pamela Schroegel ◽  
Peter Strohriegl ◽  
Anna Köhler

We present a spectroscopic investigation on the effect of changing the position where carbazole is attached to biphenyl in carbazolebiphenyl (CBP) on the triplet state energies and the propensity to excimer formation. For this, two CBP derivatives have been prepared with the carbazole moieties attached at the ( para ) 4- and 4 ′ -positions ( p CBP) and at the ( meta ) 3- and 3 ′ -positions ( m CBP) of the biphenyls. These compounds are compared to analogous m CDBP and p CDBP, i.e. two highly twisted carbazoledimethylbiphenyls, which have a high triplet energy at about 3.0 eV and tend to form triplet excimers in a neat film. This torsion in the structure is associated with localization of the excited state onto the carbazole moieties. We find that in m CBP and p CBP, excimer formation is prevented by localization of the triplet excited state onto the central moiety. As conjugation can continue from the central biphenyls into the nitrogen of the carbazole in the para -connected p CBP, emission involves mainly the benzidine. By contrast, the meta -linkage in m CBP limits conjugation to the central biphenyl. The associated shorter conjugation length is the reason for the higher triplet energy of 2.8 eV in m CBP compared with the 2.65 eV in p CBP.


Author(s):  
So Yoon Kwon ◽  
Ki-Cheol Yoon ◽  
Kwang Gi Kim

Abstract Most brain surgeries aim to completely resection a tumor. However, the arrangement of blood vessels around brain tumors is often complex. Moreover, the tumors and blood vessels have similar colors, making it difficult to identify the boundaries between them with the naked eye. Fluorescent staining is a method used to distinguish the borders between brain tumors and blood vessels. The fluorescent contrast agents commonly used to observe tumors are 5-aminolevulinic acid (5-ALA) and fluorescein sodium (FS), which have different surgical sensitivities, depending on the type of tumor. In this article, a dual band band-pass filter (BPF) with dual-wavelength emission for 5-ALA and FS is designed, and the dual-band BPF capable of inducing simultaneous fluorescence emission of FS and 5-ALA was investigated experimentally to improve accuracy, speed, and energy efficiency in clinical settings. The possibility of dual fluorescence emission with a single irradiation is proposed. The proposed fluorescent dual-band filter has the advantage of saving energy, reducing auxiliary manpower and unit costs, and reducing operating room space requirements by producing two fluorescence diagnostic effects using a single equipment.


1995 ◽  
Vol 413 ◽  
Author(s):  
Richard M. Tarkka ◽  
Samson A. Jenekhe

ABSTRACTExcited state intramolecular proton transfer (ESIPT) has been demonstrated in new intramoleculary hydrogen bonded (IHB) polymers of interest as photostabilizers, triplet quenchers, photochromic materials, laser dyes and electroluminescent materials. The new IHB polymers containing the 2-(2-hydroxyphenyl)benzoxazole moiety in the main chain were used to explore the effects of polymer structure, extended conjugation and competition with excimer formation on the ESIPT process. It was found that polymer structure, and particularly extent of conjugation, affects an IHB polymer's ability to exhibit ESIPT.


1993 ◽  
Vol 215 (6) ◽  
pp. 641-648 ◽  
Author(s):  
Hiroshi Sekiya ◽  
Mariko Habu ◽  
Hiroki Ujita ◽  
Takeshi Tsuji ◽  
Akira Mori ◽  
...  

Author(s):  
Jorge Aguilera ◽  
Víctor García-González ◽  
Manuel Alatorre-Meda ◽  
Eustolia Rodríguez-Velázquez ◽  
Ignacio Rivero

In this work, we explored the synthesis of 4,4-difluoro-4-bora-3a,4a-diazas-indacene (BODIPYs) bound to five different amino acids (BODIPY-FAA) (glycine, alanine, leucine, phenylalanine, and tyrosine) (amino group is kept protected with fluorophore Fmoc) and evaluated these conjugates in terms of (i) their photophysical properties and (ii) their potential application as cell staining agents of suspension and adherent cells at healthy and stress conditions. In general, all synthesized BODIPY-FAA (3a-3e) were found to emit fluorescence in the blue and green regions of the spectrum (depending on the solvent conditions). However, BODIPY-FTyr(trt) (3e) showed the best molar extinction coefficient (ε = 28,198 M-1 cm-1) and quantum yield (Φ = 0.17). Biologically speaking, all synthesized conjugates demonstrated a selective affinity for the cytoplasm of Langerhans β-cells employed as a model, being the BODIPY-FLeu conjugate the one displaying the highest observed intensity. As such, our results reveal the BODIPY-FAA as a novel attractive tool for the specific staining of the cell cytoplasm, demonstrating not only a dual fluorescence emission but also a sensing capability to recognize different cell states.


Author(s):  
Gang Wang ◽  
Nannan Ding ◽  
Hongxing Hao ◽  
Qingwei Jiang ◽  
Qianqian Feng ◽  
...  

Realizing single-molecule dual fluorescence with facile tunability in both the solution and film states through manipulating the excited-state relaxation pathways is highly desirable but challenging. Herein, three synthesized fluorophores emit...


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