Photophysics of some substituted 3H-indole probe molecules and their charged species

1994 ◽  
Vol 72 (11) ◽  
pp. 2239-2248 ◽  
Author(s):  
Michel Belletête ◽  
Ranjit S. Sarpal ◽  
Gilles Durocher
Keyword(s):  
Excited State ◽  
Radiative Decay ◽  
Mirror Image ◽  
Good Tool ◽  
Decay Rate Constant ◽  
Solvent Interactions ◽  
Cationic Species ◽  
Photophysical Parameters ◽  
Ring Nitrogen ◽  
Ring Nitrogen Atom

The spectroscopic and photophysical parameters of neutral and cationic species of the following molecules have been discussed: 2-phenyl-3,3-dimethyl-3H-indole (1), 2-[(p-amino)phenyl]-3,3-dimethyl-3H-indole (2), 2-[(p-dimethylamino)phenyl]-3,3-dimethyl-3H-indole (3), 2-[(p-amino)phenyl]-3,3-dimethyl-5-carboethoxy-3H-indole (4), 2-[(p-methylamino)phenyl]-3,3-dimethyl-5-carboethoxy-3H-indole (5), 2-[(p-dimethylamino)phenyl]-3,3-dimethyl-5-carboethoxy-3H-indole (6). Solvatochromic shifts have been interpreted in terms of the nature of the substituent groups and the state of solute–solvent interactions and complexation. The theoretical radiative decay rate constant [Formula: see text] along with the bandwidth of the absorption profile of the different species involved have been used to discuss the geometrical changes from one species to the other in the ground state. The mirror-image relationship between absorption and fluorescence spectra has proven to be a good tool to discuss any geometrical changes occurring in the excited state. A radiationless torsional mechanism takes place in the excited state relaxation of the various species. The protonation of the ring nitrogen atom generates a highly planar cationic species which retains its conformation in the relaxed excited state. The very effective quenching of the monocation fluorescence is interpreted by the formation of a non-emissive TICT state.

Taming the excited state reactivity of imines – from non-radiative decay to aza Paternò–Büchi reaction

2021 ◽  
Author(s):  
Sunil Kumar Kandappa ◽  
Lakshmy Kannadi Valloli ◽  
Sapna Ahuja ◽  
Jayachandran Parthiban ◽  
J. Sivaguru
Keyword(s):  
Excited State ◽  
Radiative Decay ◽  
Photophysical Properties

This review highlights the excited state characteristics of imines and processes that govern their photochemical and photophysical properties.

One-pot synthesis of N-substituted-3-hydroxy-4-pyridinone chelate complexes of aluminum, gallium, and indium

1989 ◽  
Vol 67 (11) ◽  
pp. 1708-1710 ◽  
Author(s):  
Zaihui Zhang ◽  
T. L. Thomas Hui ◽  
Chris Orvig
Keyword(s):  
Metal Ions ◽  
Metal Ion ◽  
Nucleophilic Attack ◽  
Electronic Effects ◽  
One Pot ◽  
Group 13 ◽  
Pyrone Ring ◽  
One Pot Synthesis ◽  
Ring Nitrogen ◽  
Ring Nitrogen Atom

A series of tris(3-hydroxy-2-methyl-4-pyridinonato)metal(III) and tris(3-hydroxy-6-hydroxymethyl-4-pyridinonato)metal(III) complexes have been prepared in water by one-pot synthesis directly from maltol and kojic acid, respectively, and the metal ion (M = Al, Ga, In) with an appropriate amine. The pyridinones have substituents at the ring nitrogen atom (CH3, C2H5). The tris(3-hydroxy-4-pyronato)metal(III) complexes are formed insitu and these undergo nucleophilic attack by the primary amine; the appropriate tris(3-hydroxy-4-pyridinonato)metal(III) complexes are obtained. This method bypasses the sequential syntheses of ligand and metal complex, and has improved the yields of the tris(ligand)metal complexes, in particular by making them much more easily accessible. The electronic effects of binding the pyrone to the metal ions and of the substituents on the pyrone ring on the reactivity are discussed. Keywords: 3-hydroxy-4 pyridinone complexes, group 13 metal ions, one-pot synthesis.

scholarly journals Excited State Dynamics of 8-Vinyldeoxyguanosine in Aqueous Solution Studied by Time-Resolved Fluorescence Spectroscopy and Quantum Mechanical Calculations

Molecules ◽  
2020 ◽  
Vol 25 (4) ◽  
pp. 824
Author(s):  
Lara Martinez-Fernandez ◽  
Thomas Gustavsson ◽  
Ulf Diederichsen ◽  
Roberto Improta
Keyword(s):  
Excited State ◽  
Density Functional ◽  
Radiative Decay ◽  
Decay Channel ◽  
Photophysical Properties ◽  
Time Resolved ◽  
Td Dft ◽  
Bonding Properties ◽  
Purine Ring ◽  
Vinyl Group

The fluorescent base guanine analog, 8-vinyl-deoxyguanosine (8vdG), is studied in solution using a combination of optical spectroscopies, notably femtosecond fluorescence upconversion and quantum chemical calculations, based on time-dependent density functional theory (TD-DFT) and including solvent effect by using a mixed discrete-continuum model. In all investigated solvents, the fluorescence is very long lived (3–4 ns), emanating from a stable excited state minimum with pronounced intramolecular charge-transfer character. The main non-radiative decay channel features a sizeable energy barrier and it is affected by the polarity and the H-bonding properties of the solvent. Calculations provide a picture of dynamical solvation effects fully consistent with the experimental results and show that the photophysical properties of 8vdG are modulated by the orientation of the vinyl group with respect to the purine ring, which in turn depends on the solvent. These findings may have importance for the understanding of the fluorescence properties of 8vdG when incorporated in a DNA helix.

Excited state intramolecular proton transfer in 2-(2'-hydroxyphenyl)-1H-naphth-[2,3-d]-imidazole: effects of solvents and pH

2000 ◽  
Vol 78 (2) ◽  
pp. 191-205 ◽  
Author(s):  
Somes K Das ◽  
G Krishnamoorthy ◽  
Sneh K Dogra
Keyword(s):  
Excited State ◽  
Proton Transfer ◽  
Radiative Decay ◽  
Intramolecular Proton Transfer ◽  
Normal Band ◽  
Am1 Method ◽  
Excitation Spectra ◽  
Fluorescence Excitation ◽  
Protic Solvents ◽  
Fluorescence Excitation Spectra

The solvent dependent study of absorption, fluorescence, and fluorescence excitation spectra of 2-(2'-hydroxyphenyl)-1H-naphth-[2,3-d]-imidazole (HPNI) have indicated the presence of different rotamers and tautomers in the So and S1 states. Similarity of the absorption and fluorescence spectra of HPNI in protic solvents with those of 2-(2'-methoxyphenyl)-1H-naphth-[2,3-d]-imidazole (MPNI) suggests that the normal emission is observed from the rotamers 2 and 4, whereas the tautomer emission is observed from the tautomer 3, formed by the excited state intramolecular proton transfer (ESIPT) in the rotamer 1 (Scheme 1). Ground state geometries of rotamers 1, 2, and the tautomer 3 were optimized using AM1 method. The results show that the rotamer 2 is the most stable and its stability further increases in polar and protic solvents due to the dipolar solvation interaction. The increase in the fluorescence quantum yield of the normal band when methanol or water is added to dioxane is due to: (i) the formation of rotamer 4, where ESIPT is not possible and (ii) the decrease in the rate of non-radiative decay process. Very large red shifted fluorescence bands of the monocations of HPNI and MPNI in different solvents have been assigned to the charge transfer band.Key words: 2-(2'-hydroxyphenyl)-1H-naphth-[2,3-d]-imidazole, ESIPT, prototropic reactions, fluorescence, 2-(2'-methoxyphenyl)-1H-naphth-[2,3-d]-imidazole.

Übergangsmetallkomplexe mit Nitroxidradikalen: Palladium-, Platin-, Pentamethylcyclopentadienyl-rhodium- und -iridium-Komplexe sowie α-Aminocarboxylatkomplexe mit Donor-haltigen Derivaten des 2,5-Dihydroimidazol-l-oxyls / Transition Metal Complexes of Nitroxide Radicals, Palladium, Platinum, Pentamethylcyclopentadienyl Rhodium and Iridium Complexes, and α-Aminocarboxylate Complexes with Derivatives of 2,5-Dihydroimidazole-l-oxyls

1998 ◽  
Vol 53 (1) ◽  
pp. 101-109 ◽  
Author(s):  
Frank Hintermaier ◽  
Sylvia Helding ◽  
Leonid B. Volodarsky ◽  
Karlheinz Sünkel ◽  
Kurt Polbom ◽  
...  
Keyword(s):  
Nitrogen Atom ◽  
Molecular Structures ◽  
Iridium Complexes ◽  
X Ray Diffraction ◽  
Chelate Complexes ◽  
X Ray ◽  
Ring Nitrogen ◽  
Derivatives Of ◽  
Ring Nitrogen Atom ◽  
Palladium Platinum

2,5-Dihydroimidazoline-l-oxyl radicals I, II with imino substituents coordinate to Pd(II) and Pt(II) complexes with formation of the N,N chelate complexes 1-6. With oxygen containing substituents either monodentate N-coordination to give 8 or N ,O chelate formation to give 9 takes place, depending on the position of the oxygen atom relative to the ring nitrogen atom. With radicals III that also have the second ring nitrogen atom oxidized and the Rh(III) or Ir(III) complexes [Cp*MCl2]2 the O , O chelates 11 -13 could be obtained, while with Na2PdCl4 the heterocycle was destroyed with formation of a N,N chelate complex 10 of an α-nitrosooxime ligand. The orthopalladated 2,2,5,5 tetramethyl-4-phenyl-2,5-dihydroimidazoline-l-oxyl complex 7a reacts with several a-amino acidates under splitting of the dichloro bridge with formation of the C,N/N,O-bis-chelate complexes 7b-f. The molecular structures of 2 and 10 were determined by X-ray diffraction.

The influence of phenylethynyl linkers on the photo-physical properties of metal-free porphyrins

2000 ◽  
Vol 04 (07) ◽  
pp. 669-683 ◽  
Author(s):  
GARY A. BAKER ◽  
FRANK V. BRIGHT ◽  
MICHAEL R. DETTY ◽  
SIDDHARTH PANDEY ◽  
COREY E. STILTS ◽  
...  
Keyword(s):  
Excited State ◽  
Radiative Decay ◽  
Phenyl Group ◽  
Quantum Yields ◽  
Fluorescence Lifetimes ◽  
Strongly Coupled ◽  
Metal Free ◽  
Fluorescence Quantum Yields ◽  
Porphyrin Core ◽  
Absorbance Spectra

Series of 5,10,15,20-tetraarylporphyrins 1 and 5,10,15,20-tetrakis[4-(arylethynyl)phenyl]porphyrins 2 were prepared via condensation of pyrrole with the appropriate benzaldehyde or 4-(arylethynyl)benzaldehyde derivative (3). Condensation of meso-phenyldipyrromethane with mixtures of benzaldehyde and 4-(trimethylsilyl-ethynyl)benzaldehyde gave a separable mixture of mono- (6), bis- (both cis-7 and trans-8) and tris[4-(trimethylsilylethynyl)phenyl]porphyrin (9). Following removal of the trimethylsilyl groups of 6–9, the 4-ethynylphenyl groups of 11–14 were coupled to 1-iodo-3,5-di(trifluoromethyl)benzene with Pd ( OAc )2 to give 15–18 bearing one, two (both cis- and trans-) and three 4-[bis-3,5-(trifluoromethyl)phenylethynyl]phenyl groups respectively. Coupling of 11 and 1-iodo-4-nitrobenzene with Pd ( OAc )2 gave porphyrin 19 with one 4-(4-nitrophenylethynyl)phenyl group. Porphyrin 24 with a p-quinone linked to the porphyrin core via a phenylethynyl group was prepared via similar chemistry. The absorbance spectra, emission maxima, excited-state fluorescence lifetimes, quantum yields of fluorescence, rates of fluorescence and rates of non-radiative decay were measured for each of the porphyrins. Absorbance spectra and emission maxima were nearly identical for all the porphyrins of this study, which suggests that the aryl groups and 4-(arylethynyl)phenyl groups are not strongly coupled to the porphyrin core in these metal-free compounds. Fluorescence quantum yields and rates of radiative decay were larger for porphyrins bearing 4-(arylethynyl)phenyl groups, while excited-state fluorescence lifetimes were somewhat shorter. These effects were additive for each additional 4-(arylethynyl)phenyl group.

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