scholarly journals Mono-, Di-, Tri-Pyrene Substituted Cyclic Triimidazole: A Family of Highly Emissive and RTP Chromophores

Photochem ◽  
2021 ◽  
Vol 1 (3) ◽  
pp. 477-487
Author(s):  
Daniele Malpicci ◽  
Clelia Giannini ◽  
Elena Lucenti ◽  
Alessandra Forni ◽  
Daniele Marinotto ◽  
...  
Keyword(s):  
Steady State ◽  
Solid State ◽  
Intermolecular Interactions ◽  
Quantum Yields ◽  
Time Resolved ◽  
Tddft Calculations ◽  
Pyrene Molecule ◽  
The Family ◽  
Strong Motivation

The search of new organic emitters is receiving a strong motivation by the development of ORTP materials. In the present study we report on the preparation, optical and photophysical characterization, by both steady state and time resolved techniques, of two pyrene-functionalized cyclic triimidazole derivatives. Together with the already reported mono-substituted derivative, the di- and tri-substituted members of the family have revealed as intriguing emitters characterized by impressive quantum yields in solution and RTP properties in the solid state. In particular, phosphorescence lifetimes increase from 5.19 to 20.54 and 40.62 ms for mono-, di- and trisubstituted compounds, respectively. Based on spectroscopical results and theoretical DFT/TDDFT calculations on the di-pyrene molecule, differences in photophysical performances of the three compounds have been assigned to intermolecular interactions increasing with the number of pyrene moieties appended to the cyclic triimidazole scaffold.

scholarly journals Emission Quenching in Tetraphenylfuran Crystal: Why This Propeller-Shaped Molecule Does Not Emit in the Condensed Phase?

Molecules ◽  
2022 ◽  
Vol 27 (2) ◽  
pp. 522
Author(s):  
Ljiljana Stojanović ◽  
Rachel Crespo-Otero
Keyword(s):  
Solid State ◽  
Ground State ◽  
Light Emission ◽  
Quantum Yields ◽  
Triplet States ◽  
Fluorescence Quantum Yields ◽  
The Family ◽  
Emission Quenching ◽  
Significant Attention

Due to their substantial fluorescence quantum yields in the crystalline phase, propeller-shaped molecules have recently gained significant attention as potential emissive materials for optoelectronic applications. For the family of cyclopentadiene derivatives, light-emission is highly dependent on the nature of heteroatomic substitutions. In this paper, we investigate excited state relaxation pathways in the tetraphenyl-furan molecule (TPF), which in contrast with other molecules in the family, shows emission quenching in the solid-state. For the singlet manifold, our calculations show nonradiative pathways associated with C-O elongation are blocked in both vacuum and the solid state. A fraction of the population can be transferred to the triplet manifold and, subsequently, to the ground state in both phases. This process is expected to be relatively slow due to the small spin-orbit couplings between the relevant singlet-triplet states. Emission quenching in crystalline TPF seems to be in line with more efficient exciton hopping rates. Our simulations help clarify the role of conical intersections, population of the triplet states and crystalline structure in the emissive response of propeller-shaped molecules.

Spectrofluorimetric Study on Inclusion Complexation of 2-Amino-6-fluorobenzothiazole with β-Cyclodextrin

2008 ◽  
Vol 73 (2) ◽  
pp. 147-160 ◽  
Author(s):  
Rajaram Rajamohan ◽  
Sundarajulu Kothai Nayaki ◽  
Meenakshisundaram Swaminathan
Keyword(s):  
Aqueous Solution ◽  
Steady State ◽  
Solid State ◽  
Inclusion Complex ◽  
Inclusion Complexation ◽  
Solid Complex ◽  
Time Resolved Fluorescence ◽  
Sem Images ◽  
Time Resolved ◽  
Ft Ir

The interaction between 2-amino-6-fluorobenzothiazole (AFBT) and β-cyclodextrin (β-CDx) has been investigated in aqueous solution and in the solid state. The stoichiometry and binding constant of the complex between AFBT and β-CDx in solution were determined by steady-state and time-resolved fluorescence spectroscopy. The FT-IR spectral data and SEM images of the solid complex confirmed the formation of inclusion complex. The proton transfer behaviour of AFBT has been investigated in aqueous and β-CDx solutions.

Photophysics of Carbazole-Containing Systems. 2. Fluorescence Behaviour of Poly(N-Vinyl Carbazole) and N -Vinyl Carbazole/Methyl Acrylate Copolymer Films

1997 ◽  
Vol 9 (4) ◽  
pp. 353-367 ◽  
Author(s):  
Ian Soutar ◽  
Linda Swanson ◽  
Keith Davidson ◽  
Jie Yin
Keyword(s):  
Steady State ◽  
Intermolecular Interactions ◽  
Methyl Acrylate ◽  
Moderating Effects ◽  
Aromatic Rings ◽  
High Concentration ◽  
Time Resolved ◽  
Copolymer Films ◽  
Acrylate Copolymer ◽  
Dominant Influence

The fluorescence behaviour of thin films of poly( N-vinyl carbazole), PNVCz, and a series of N-vinyl carbazole/methyl acrylate, NVCz/MA, copolymers has been investigated using both steady-state and time-resolved emission techniques. The fluorescence of PNVCz at 298 K is dominated by emission from two excimeric traps. Trap I has the conventional ‘sandwich’ structure formed from two fully overlapped aromatic rings. The other (trap II) is a species involving two partially overlapped carbazole substituents. The fluorescences of the NVCz/MA copolymers contain contributions from unassociated or monomeric carbazoyl excited states which increase in prominence as the aromatic content of the system is reduced. The influence of intermolecular interactions in creating excimer traps is apparent: even at a carbazole content of 8.3 mol%, excimer emission is evident. In PNVCz and copolymers of higher aromatic contents, the microtacticity of the macromolecule exerts a dominant influence upon the photophysical behaviour of the bulk polymer despite the moderating effects of intermolecular interactions between chromophores. As the temperature of the system is reduced, the contribution from trap II to the overall fluorescence from the polymer films increases relative to that made by emission from trap I. At 77 K, the fluorescence of PNVCz contains a significant contribution from trap II emission. At 298 K, fluorescence from the conventional excimer, trap I, dominates the steady-state emission spectrum. On the basis of observations upon time-resolved fluorescence data, it is proposed that restrictions to the reorientation of carbazole substituents which occur at low temperature serve to inhibit the conversion of a proportion of the trap II sites into fully overlapped excimers, thereby reducing depletion of the trap II population. Implicit to this explanation of the photophysical characteristics of PNVCz and the higher content NVCz/MA copolymers, is the belief that the high concentration of excimer-forming trap sites mitigates against significant energy migration between carbazole substituents which might otherwise populate the excimer traps. These observations are of importance to considerations of the photoconductivity displayed by polymers derived from NVCz.

Visualization and Manipulation of Molecular Motion in Solid State through Photo-Induced Clusteroluminescence

2019 ◽  
Author(s):  
Haoke Zhang ◽  
Lili Du ◽  
Lin Wang ◽  
Junkai Liu ◽  
Qing Wan ◽  
...  
Keyword(s):  
Quantum Mechanics ◽  
Excited State ◽  
Solid State ◽  
Light Source ◽  
Molecular Motion ◽  
Molecular Machine ◽  
Conjugated Molecules ◽  
Time Resolved ◽  
Packing Structure ◽  
New Strategy

<p>Building molecular machine has long been a dream of scientists as it is expected to revolutionize many aspects of technology and medicine. Implementing the solid-state molecular motion is the prerequisite for a practical molecular machine. However, few works on solid-state molecular motion have been reported and it is almost impossible to “see” the motion even if it happens. Here the light-driven molecular motion in solid state is discovered in two non-conjugated molecules <i>s</i>-DPE and <i>s</i>-DPE-TM, resulting in the formation of excited-state though-space complex (ESTSC). Meanwhile, the newly formed ESTSC generates an abnormal visible emission which is termed as clusteroluminescence. Notably, the original packing structure can recover from ESTSC when the light source is removed. These processes have been confirmed by time-resolved spectroscopy and quantum mechanics calculation. This work provides a new strategy to manipulate and “see” solid-state molecular motion and gains new insights into the mechanistic picture of clusteroluminescence.<br></p>

scholarly journals Convenient Access to Functionalized Non-Symmetrical Atropisomeric 4,4′-Bipyridines

Compounds ◽  
2021 ◽  
Vol 1 (2) ◽  
pp. 58-74
Author(s):  
Emmanuel Aubert ◽  
Emmanuel Wenger ◽  
Paola Peluso ◽  
Victor Mamane
Keyword(s):  
Solid State ◽  
Intermolecular Interactions ◽  
Medicinal Chemistry ◽  
Crystal Packing ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Halogen Bonds ◽  
Cross Coupling Reactions ◽  
Cyano Groups ◽  
Post Functionalization

Non-symmetrical chiral 4,4′-bipyridines have recently found interest in organocatalysis and medicinal chemistry. In this regard, the development of efficient methods for their synthesis is highly desirable. Herein, a series of non-symmetrical atropisomeric polyhalogenated 4,4′-bipyridines were prepared and further functionalized by using cross-coupling reactions. The desymmetrization step is based on the N-oxidation of one of the two pyridine rings of the 4,4′-bipyridine skeleton. The main advantage of this methodology is the possible post-functionalization of the pyridine N-oxide, allowing selective introduction of chlorine, bromine or cyano groups in 2- and 2′-postions of the chiral atropisomeric 4,4′-bipyridines. The crystal packing in the solid state of some newly prepared derivatives was analyzed and revealed the importance of halogen bonds in intermolecular interactions.

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