π-Electron delocalization and electronic transitions in oligomeric and polymeric phthalocyanine zinc(II) complexes. Part 1: Linear oligo- and one-dimensional polyphthalocyanines

2020 ◽  
Vol 24 (04) ◽  
pp. 515-527
Author(s):  
Sergei G. Makarov ◽  
Günter Schnurpfeil ◽  
Sergey Yu. Ketkov ◽  
Dieter Wöhrle
Keyword(s):  
Near Infrared ◽  
Energy Gap ◽  
Graphene Nanoribbons ◽  
Basis Set ◽  
Electron Delocalization ◽  
Long Wavelength ◽  
Near Infrared Spectra ◽  
Wavelength Absorption ◽  
Semi Empirical ◽  
Long Wavelength Absorption Band

In this Part 1 of our two part study, 1D-linear oligomeric phthalocyanine zinc(II) with fully annulated (fused) phthalocyanine macrocycles are described. By semi-empirical and DFT computational methods the UV-vis and near infrared spectra, including energy gaps, are thoroughly evaluated. The long-wavelength Q band of the oligophthalocyanines is compared with the long wavelength absorption band of analogous oligoacenes consisting of annulated benzene rings. In addition, graphene nanoribbons are considered. The aromaticity is especially interesting when considering Clar’s rule. Therefore it is the aim to get information about the extent of [Formula: see text]-electron delocalization in linear or semi-linear systems. Finally, the results of linear oligophthalocyanines are extrapolated to estimate the energy gap of 1D linear polyphthalocyanine by DFT, and the result is compared to the DFT calculation of the periodic structure with a plane-wave basis set. Part 2 will describe non-linear oligo- and two-dimensional polyphthalocyanines.

scholarly journals Электронное строение и спектрально-флуоресцентные свойства лазерных красителей тиопирило-4-трикарбоцианинов

2021 ◽  
Vol 129 (7) ◽  
pp. 862
Author(s):  
А.А. Ищенко ◽  
И.В. Курдюкова ◽  
М.В. Богданович ◽  
С.Л. Бондарев ◽  
А.А. Романенко ◽  
...  
Keyword(s):  
Radiative Transition ◽  
Polymethine Chain ◽  
Long Wavelength ◽  
Vibronic Interactions ◽  
Wide Range ◽  
Wavelength Absorption ◽  
Fluorescent State ◽  
Long Wavelength Absorption Band ◽  
Angle Of Rotation ◽  
Ab Initio Dft

It was found that the long-wavelength absorption band of the laser dye IR 1061 and its analogue with an unsubstituted polymethine chain is strongly broadened and decreases in intensity in polar solvents, while the fluorescence band remains narrow and practically does not change in a wide range of solvent polarities. Based on the quantum-chemical calculations of these dyes by the ab initio DFT/B3LYP/6-31G (d,p) and TDDFT methods, taking into account the polarity of the medium by the PCM method, it is shown that the reason for this difference is the weakening of solvation in the fluorescent state as compared to the ground state due to the greater equalization of the charge in the first than in the latter. An increase in the alternation of bond orders in the polymethine chain in the fluorescent state was found, which causes an increase of vibronic interactions in the radiative transition as compared to the absorptive one. Spectral effects caused by a change in the angle of rotation of phenyl groups in the thiopyrylium cycle upon excitation have been analyzed.

Erstmaliger Nachweis von π–π Dimerenbildung bei stabilen 1,4-Dialkylchinoxalinium-Radikalkationen. Struktur, Spektroskopie und Magnetismus / First Evidence for π-π-Dimerization of the Stable 1,4-Dialkylquinoxalinium Radical Cations. Structure, Spectroscopy and Magnetism

1993 ◽  
Vol 48 (9) ◽  
pp. 1181-1186 ◽  
Author(s):  
H.-D. Hausen ◽  
Wolfgang Kaim ◽  
Andreas Schulz ◽  
Michael Moscherosch ◽  
Jeanne Jordanov
Keyword(s):  
Solid State ◽  
Magnetic Measurements ◽  
Magnetic Moments ◽  
Cation Radical ◽  
Radical Cations ◽  
Long Wavelength ◽  
Wavelength Absorption ◽  
Molecular Structure Analysis ◽  
Long Wavelength Absorption Band ◽  
Quinoxaline Ring

Crystal and molecular structure analysis of 1,4-diethylquinoxalinium iodide shows a virtually planar quinoxaline ring with 11 conjugated π-electrons. In contrast to the triiodide of the 1,4,6,7-tetramethyl derivative or to the tetraphenylborate salt of 1,4-diethylquinoxalinium cation radical the iodide exhibits π-π-dimerized radical cations in the solid state with synplanar ethyl groups and a rather small intermolecular distance of about 315 pm between the π-planes of the primarily interacting 1,4-diazine rings. Solid state magnetic measurements between 2 and 300 K show considerably diminished magnetic moments due to partial spin-pairing, and UV/VIS spectroscopic measurements in acetonitrile reflect the π—π-interaction in solution through the appearance of a long-wavelength absorption band.

Elaboration of an unexplored substitution site in synthetic bacteriochlorins

2015 ◽  
Vol 19 (07) ◽  
pp. 887-902 ◽  
Author(s):  
Nuonuo Zhang ◽  
Kanumuri Ramesh Reddy ◽  
Jianbing Jiang ◽  
Masahiko Taniguchi ◽  
Roger D. Sommer ◽  
...  
Keyword(s):  
Bathochromic Shift ◽  
Fluorescence Emission ◽  
Bacterial Photosynthesis ◽  
Alkoxy Group ◽  
The Self ◽  
X Ray ◽  
Long Wavelength ◽  
Substitution Site ◽  
Wavelength Absorption ◽  
Long Wavelength Absorption Band

The ability to introduce substituents at designated sites about the perimeter of synthetic bacteriochlorins – analogs of bacteriochlorophylls of bacterial photosynthesis – remains a subject of ongoing study. Here, the self-condensation of a dihydrodipyrrin-dioxolane affords a 5-[2-(trimethylsiloxy)ethoxy]bacteriochlorin. Like a 5-methoxybacteriochlorin, the latter undergoes regioselective bromination at the 15-position, directed by the distal 5-alkoxy group. On the other hand, attempted bromination of a bacteriochlorin bearing a 5-(2-hydroxyethoxy) group resulted in intramolecular ether formation with the adjacent β-pyrroline position to give an annulated dioxepine ring (confirmed by single-crystal X-ray structural analysis). The hydroxyethoxy group at the 5-position can be derivatized by acylation. In addition, the installation of auxochromes (methoxycarbonyl, phenylethynyl) at the β-pyrrole rings causes a substantial bathochromic shift of the long-wavelength absorption band (812 nm) and companion fluorescence emission band (821 nm). Taken together, the modification of the 5-substituent complements existing methods for installing a single substituent on the bacteriochlorin macrocycle.

Synthesis and spectroscopic properties of benzo- and naphthofuryl-3-hydroxychromones

2001 ◽  
Vol 79 (4) ◽  
pp. 358-363 ◽  
Author(s):  
Andrey S Klymchenko ◽  
Turan Ozturk ◽  
Vasyl G Pivovarenko ◽  
Alexander P Demchenko
Keyword(s):  
Excited State ◽  
Proton Transfer ◽  
Spectroscopic Properties ◽  
Molecular Probe ◽  
Absorption Bands ◽  
Methyl Group ◽  
Long Wavelength ◽  
Excited State Proton Transfer ◽  
Wavelength Absorption ◽  
Long Wavelength Absorption Band

With the focus of designing new fluorescent probes, four new 3-hydroxy-chromone derivatives bearing benzofuran and naphthofuran groups were synthesized. They show bathochromic absorption shifts relative to 3-hydroxyflavone with the ability of retention to display the excited-state proton transfer. Disruption of the planarity by the methyl group in the furan ring leads to a decrease of both the extinction coefficient and the contribution of long wavelength absorption band, while molecules without a methyl group showed two distinct absorption bands. Shifts to longer wavelengths are also observed in fluorescent spectra, and the absence of the methyl group results in a dramatic increase of fluorescence quantum yield and lifetime. Of the extended 3-hydroxychromone derivatives, 3-hydroxy-2-naphtho[2,1-b]furan-2-yl-chromone has shown comparable, and in some cases better, absorption and fluorescence properties than the 3-hydroxychromones synthesized so far, which make it a highly promising candidate as molecular probe for analytical chemistry, biophysics, and cellular biology.Key words: benzo- and naphthofuryl-3-hydroxyflavone, synthesis, electronic spectra, fluorescence, excited state proton transfer.

scholarly journals The fluorescence analysis of laser photolysis of phenols in water

2002 ◽  
Vol 4 (2) ◽  
pp. 79-83 ◽  
Author(s):  
O. Tchaikovskaya ◽  
I. Sokolova ◽  
O. Bazyl ◽  
V. Swetlichnyi ◽  
T. Kopylova ◽  
...  
Keyword(s):  
Quantum Chemical ◽  
Laser Light ◽  
Fluorescence Analysis ◽  
Dynamic Changes ◽  
Long Wavelength ◽  
Chlorine Substitution ◽  
Wavelength Absorption ◽  
Chemical Techniques ◽  
Long Wavelength Absorption Band ◽  
Photolysis Of Phenol

Photolysis of phenol andp-chlorophenol exposed to KrCl- and Nd-YAG laser light is studied by electron spectroscopy and fluorescence and quantum chemical techniques. The decrease of the quantum yield of phenol fluorescence with increase in the excitation energy is not related to dynamic changes in the intramolecular photophysical processes; rather this is a result of increased photoreaction efficiency. Chlorine substitution for para-state of phenol is shown to strengthen the OH-bond in excitation into the long wavelength absorption band.

Synthesis and characterisation of long wavelength-absorbing donor/acceptor-substituted methine dyes

2016 ◽  
Vol 71 (6) ◽  
pp. 651-658
Author(s):  
Christoph Heichert ◽  
Horst Hartmann
Keyword(s):  
Spectral Range ◽  
Near Infrared ◽  
Long Wavelength ◽  
Iminium Salts ◽  
Infrared Spectral Range ◽  
Active Methylene Compounds ◽  
Infrared Spectral ◽  
Wavelength Absorption ◽  
Donor Acceptor ◽  
Active Methylene

AbstractBy the reaction of aromatic or heteroaromatic formyl compounds or their corresponding iminium salts with active methylene compounds a series of new methine dyes with long-wavelength absorption in the near-infrared spectral range were prepared.

Surface photochemistry: use of spiropyrans as indicators of surface polarity

1984 ◽  
Vol 62 (5) ◽  
pp. 1001-1002 ◽  
Author(s):  
Paul De Mayo ◽  
Ali Safarzadeh-Amiri ◽  
S. King Wong
Keyword(s):  
Absorption Band ◽  
Silica Gel ◽  
Solvent Polarity ◽  
Surface Polarity ◽  
Long Wavelength ◽  
Wavelength Absorption Band ◽  
Wavelength Absorption ◽  
Long Wavelength Absorption Band

The position of the long wavelength absorption band in the spectrum of a spiropyran is sensitive to solvent polarity. This property has been used to determine the polarity of the silica gel surface.

scholarly journals Guest-host doped strategy for constructing ultralong-lifetime near-infrared organic phosphorescence materials for bioimaging

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Fuming Xiao ◽  
Heqi Gao ◽  
Yunxiang Lei ◽  
Wenbo Dai ◽  
Miaochang Liu ◽  
...  
Keyword(s):  
Room Temperature ◽  
Near Infrared ◽  
Tumor Imaging ◽  
Energy Gap ◽  
Radiative Transition ◽  
Room Temperature Phosphorescence ◽  
Triplet Energy ◽  
Long Wavelength ◽  
Long Lifetime ◽  
First Time

AbstractOrganic near-infrared room temperature phosphorescence materials have unparalleled advantages in bioimaging due to their excellent penetrability. However, limited by the energy gap law, the near-infrared phosphorescence materials (>650 nm) are very rare, moreover, the phosphorescence lifetimes of these materials are very short. In this work, we have obtained organic room temperature phosphorescence materials with long wavelengths (600/657–681/732 nm) and long lifetimes (102–324 ms) for the first time through the guest-host doped strategy. The guest molecule has sufficient conjugation to reduce the lowest triplet energy level and the host assists the guest in exciton transfer and inhibits the non-radiative transition of guest excitons. These materials exhibit good tissue penetration in bioimaging. Thanks to the characteristic of long lifetime and long wavelength emissive phosphorescence materials, the tumor imaging in living mice with a signal to background ratio value as high as 43 is successfully realized. This work provides a practical solution for the construction of organic phosphorescence materials with both long wavelengths and long lifetimes.

Synthesis of perylene-porphyrin dyads for light-harvesting studies

2002 ◽  
Vol 06 (10) ◽  
pp. 626-642 ◽  
Author(s):  
Robert S. Loewe ◽  
Kin-ya Tomizaki ◽  
Fabien Chevalier ◽  
Jonathan S. Lindsey
Keyword(s):  
Ground State ◽  
Light Harvesting ◽  
Molecular Architecture ◽  
Efficient Energy Transfer ◽  
Aryl Group ◽  
Long Wavelength ◽  
Efficient Energy ◽  
Wavelength Absorption ◽  
Meso Position ◽  
Long Wavelength Absorption Band

The spectral coverage of porphyrin-based light-harvesting arrays can be enhanced through the use of suitable accessory pigments. Perylene-monoimide dyes can serve as valuable accessory pigments with porphyrins. To investigate the choice of perylene-monoimide and the effects of molecular architecture on light-harvesting efficacy, five perylene-porphyrin dyads were prepared. Each dyad employs a diphenylethyne linker that bridges the perylene N-imide site and the porphyrin meso-position. Three dyads incorporate a mono-phenoxy perylene at the o-, m-, or p-position of the meso-aryl group on the porphyrin. The two remaining dyads incorporate a perylene-monoimide (bearing zero or three phenoxy substituents) at the p-position of the meso-aryl group on the porphyrin. The introduction of phenoxy groups on the perylenes increases the solubility, a key requirement for use in light-harvesting arrays. The long-wavelength absorption band of the perylene shifts from 506 nm to 532 or 533 nm upon substitution with one or three phenoxy groups, respectively. The synthesis of the dyads entails Pd -mediated coupling of a bromo-perylene and an ethynyl porphyrin, or the mixed-aldehyde condensation with a perylene-aldehyde, mesitaldehyde, and pyrrole. Five perylene-monoimide dyes bearing an ethyne or bromo substituent at the p-position of the N-aryl unit were developed for this modular chemistry. Each perylene-porphyrin dyad exhibits efficient energy transfer from the excited perylene to the ground-state porphyrin.

scholarly journals NeoR, a near-infrared absorbing rhodopsin

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Matthias Broser ◽  
Anika Spreen ◽  
Patrick E. Konold ◽  
Enrico Peter ◽  
Suliman Adam ◽  
...  
Keyword(s):  
Near Infrared ◽  
Fluorescence Yield ◽  
Visual Orientation ◽  
Light Activation ◽  
Long Wavelength ◽  
Wavelength Absorption ◽  
Retinal Chromophore ◽  
Fluorescent State ◽  
Photochemical Properties ◽  
High Fluorescence

Abstract The Rhizoclosmatium globosum genome encodes three rhodopsin-guanylyl cyclases (RGCs), which are predicted to facilitate visual orientation of the fungal zoospores. Here, we show that RGC1 and RGC2 function as light-activated cyclases only upon heterodimerization with RGC3 (NeoR). RGC1/2 utilize conventional green or blue-light-sensitive rhodopsins (λmax = 550 and 480 nm, respectively), with short-lived signaling states, responsible for light-activation of the enzyme. The bistable NeoR is photoswitchable between a near-infrared-sensitive (NIR, λmax = 690 nm) highly fluorescent state (QF = 0.2) and a UV-sensitive non-fluorescent state, thereby modulating the activity by NIR pre-illumination. No other rhodopsin has been reported so far to be functional as a heterooligomer, or as having such a long wavelength absorption or high fluorescence yield. Site-specific mutagenesis and hybrid quantum mechanics/molecular mechanics simulations support the idea that the unusual photochemical properties result from the rigidity of the retinal chromophore and a unique counterion triad composed of two glutamic and one aspartic acids. These findings substantially expand our understanding of the natural potential and limitations of spectral tuning in rhodopsin photoreceptors.

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