Synthesis of arylazoles and their luminescent properties

Andreeshchev, E. A.; Viktorova, V. S.; Kilin, S. F.; Kovyrzina, K. A.; Kosyakina, L. N.; Kushakevich, Yu. P.; Rozman, I.M.; Chkhikvadze, Yu. G.

doi:10.1007/bf00471814

Cited by 3 publications

(4 citation statements)

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“…Their UV/Vis spectra are similar in shape, with maximum absorption wavelengths (λ max ) of 335 nm and 337 nm for (oP 4 ) 3 and (oP 6 ) 3 , respectively. These spectra are a close match to that of (E)-4,4′-diphenylstilbene (λ max = 342 nm), [59,60] which represents a single side of each macrocycle excluding conjugation through the o-phenylene moieties. Curiously, despite the structural and spectral similarities, the macrocycles show significantly different absorptivities (ε), with that of (oP 6 ) 3 approximately double that of (oP 4 ) 3 [(7.9 ± 0.6) × 10 4 M -1 vs. TD-DFT calculations at the CAM-B3LYP/6-311+G(2d,2p) level do a good job of matching the experimental spectra in terms of λ max , although the difference in ε is not reproduced.…”

Section: Structural Analysis Of (Op 6 )mentioning

confidence: 55%

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ortho‐Phenylene‐Based Macrocyclic Hydrocarbons Assembled Using Olefin Metathesis

et al. 2020

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While many foldamer systems reliably fold into well‐defined secondary structures, higher order structure remains a challenge. A simple strategy for the organization of folded subunits in space is to link them together within a macrocycle. Previous work has shown that o‐phenylenes can be co‐assembled with rod‐shaped linkers into twisted macrocycles, showing an interesting synergy between folding and thermodynamically controlled macrocyclization. In these systems the foldamer units were largely decoupled from each other both conformationally and electronically. Here, we show that hydrocarbon macrocycles, with very short ethenylene linkers, can be assembled from o‐phenylenes using olefin metathesis. Characterization by NMR spectroscopy, X‐ray crystallography, and ab initio calculations shows that the products are approximately triangular trimer macrocycles with helical o‐phenylene corners in a heterochiral configuration. Their photophysics are dominated by the 4,4'‐diphenylstilbene moieties, the longest conjugated segments, with further conjugation broken by the twisting of the o‐phenylenes.

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Section: Structural Analysis Of (Op 6 )mentioning

confidence: 55%

“…The fluorescence spectra (Figure ) are likewise similar and a good match to that of 4,4'‐diphenylstilbene . Both macrocycles are strongly fluorescent, with quantum yields of 0.88 and 0.81 for (oP 4 ) 3 and (oP 6 ) 3 , respectively (which are indistinguishable within experimental uncertainty).…”

Section: Resultsmentioning

confidence: 99%

ortho‐Phenylene‐Based Macrocyclic Hydrocarbons Assembled Using Olefin Metathesis

et al. 2020

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“…(13), and N-(trimethylsilylmethyl) cyclohexylamine were prepared according to literature methods. [23][24][25][26][27] The experimental details for compounds 6, 11, and 19 will be reported elsewhere. The spectroscopic data and melting points of silicon-containing products 3 a-d, [28,29] 4 a-d, and 8 a-c are listed in Table 3.…”

Section: Methodsmentioning

confidence: 99%

Design, Synthesis, and Photodegradation of Silicon‐Containing Polyureas

Hwu

King

2005

Chemistry A European J

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Novel N-phenyl aromatic polyureas containing bis[(N,N'-diphenylureylene)methyl]silane units in the skeleton were designed as a new type of photodegradable polymer. These materials were successfully prepared in 88-93 % yields by copolymerization of bis(anilinomethyl)dimethylsilane and dianilino-p-xylene with 4,4'-methylenebis(phenylisocyanate). Their photodegradability was found to be 10.1 times higher than that of polymers of similar structure, but lacking the silyl unit. Furthermore, the photodegradation mechanism of polyureas was elucidated, and involves single-electron transfer between silyl and carbonyl groups, silyl group migration, and solvolysis. These novel polymers are potential materials of high economic value for use in photolithography and microelectronics.

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“…This class will not be discussed here. Table I contains a selection of solutes/solvents (or vapors) that appear to approach Kennard-Stepanov ideal conditions [17][18][19][20][21][22][23]. We do not show error estimates, because the requisite information is not available from most of these old papers and it was apparently seldom considered necessary to publish known uncertainties.…”

Section: Historical Examples Of Apparently Linear F(e)mentioning

confidence: 99%

Excited-State Equilibration and the Fluorescence-Absorption Ratio

Knox

1999

Acta Phys. Pol. A

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In any complex system at temperature T the absorption cross-section and fluorescent power at a given photon energy are connected by a simple relation if the system is in thermal equilibrium while occupying one particular electronic excited state. Although this situation is impossible in principle because of finite excited-state lifetimes, it is often approximated to the extent that the simple relation, which is expressed as a linear function of energy with slope -1/kBT, holds in a variety of cases. (The usual symbols for Boltzmann's constant and absolute temperature are used.) Observed deviations are of two principal kinds: a slope characteristic of some temperature T* other than ambient, and departures from a single pure straight line. The latter may include seemingly random variations and in some cases multiple regions of straight-line behavior. We have recently introduced an effective temperature T* (E), derived from the actual local slope of the putative straight line at energy E, which turns out to be a very sensitive detector of deviations from the ideal and, we believe, from equilibrium in the excited state. Plots of T* (E) display a variety of features. An anomaly in the T* (E) spectrum of chlorophyll a can be analyzed on this model, indicating a second weakly fluorescent state about 70 meV below the well-known Qy band. The cases of chlorophyll and many others are included in a selective review of applications of the universal relation to fluorescent systems.

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Synthesis of arylazoles and their luminescent properties

Cited by 3 publications

References 5 publications

ortho‐Phenylene‐Based Macrocyclic Hydrocarbons Assembled Using Olefin Metathesis

ortho‐Phenylene‐Based Macrocyclic Hydrocarbons Assembled Using Olefin Metathesis

Design, Synthesis, and Photodegradation of Silicon‐Containing Polyureas

Excited-State Equilibration and the Fluorescence-Absorption Ratio

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