Synthesis, characterization and optical properties of aryl and diaryl substituted phenanthroimidazoles

Nayak, Manoj K.

doi:10.1016/j.jphotochem.2012.05.018

Cited by 50 publications

(8 citation statements)

References 80 publications

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“…Excited-state intramolecular proton transfer (ESIPT) reaction has been an issue to receive considerable attention and numerous investigations on the hydroxyl-type ESIPT have been published. − In contrast to the prosperous research activities on the hydroxyl-type ESIPT, much less attention has been paid to the amino-type ESIPT. − The main reason is that the low acidity of the proton on the amino group that prohibits ESIPT and chemical modifications are needed to facilitate proton transfer. − …”

Section: Introductionmentioning

confidence: 99%

Insight into the Amino-Type Excited-State Intramolecular Proton Transfer Cycle Using N-Tosyl Derivatives of 2-(2′-Aminophenyl)benzothiazole

et al. 2016

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Studies have been carried out to gain insight in to an overall excited-state proton transfer cycle for a series of N-tosyl derivatives of 2-(2'-aminophenyl)benzothiazole. The results indicate that followed by ultrafast (<150 fs) excited-state intramolecular proton transfer (ESIPT), the titled compounds undergo rotational isomerization along the C1-C1' bond. For the model compound 2-(2'-tosylaminophenyl)benzothiazole (PBT-NHTs) the subsequent cis-trans isomerization process in both triplet and ground states are probed by nanosecond transient absorption (TA) and two-step laser-induced fluorescence (TSLIF) spectroscopy. Both TA and TSLIF results indicate the existence of a long-lived trans-tautomer species in the ground state with a lifetime of few microseconds. The experimental results correlate well with the theoretical approach, which suggests that PBT-NHTs proton transfer tautomer generated in the excited state undergoes intramolecular C1-C1' rotation to ∼100° between benzothiazole and phenyl moieties in which the energetics for the S1 and T1 states are nearly identical. As a result, the intersystem crossing between S1 and T1 states serves as a fast deactivation pathway for the excited-state cis-tautomer to channel into both cis- and trans-tautomer in their respective T1 states, followed by the dominant T1-S0 radiationless deactivation to populate the trans-tautomer in the ground state. The trans-tautomer species in the S0 state proceeds with intermolecular double proton transfer to regenerate the cis-normal form. An overall proton-transfer cycle describing the amino-type ESIPT and the subsequent isomerization processes is thus depicted in detail.

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Section: Introductionmentioning

confidence: 99%

Insight into the Amino-Type Excited-State Intramolecular Proton Transfer Cycle Using N-Tosyl Derivatives of 2-(2′-Aminophenyl)benzothiazole

et al. 2016

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“…Excited-state intramolecular proton transfer (ESIPT) reaction has been receiving considerable attention. In sharp contrast to the multitude of papers reporting hydroxyl-type ESIPT, − a search of the literature indicates that only a few reports have dealt with amino-type ESIPT using primary amines as proton donors. − The scarcity of relevant reports is due to the much weaker intramolecular hydrogen bond (H-bond) associated with the amino N–H proton (cf. the O–H type H-bond).…”

mentioning

confidence: 99%

Harnessing Excited-State Intramolecular Proton-Transfer Reaction via a Series of Amino-Type Hydrogen-Bonding Molecules

Tseng

Liu

Chen

et al. 2015

J. Phys. Chem. Lett.

217

139

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A series of new amino (NH)-type hydrogen-bonding (H-bonding) compounds comprising 2-(2'-aminophenyl)benzothiazole and its extensive derivatives were designed and synthesized. Unlike in the hydroxyl (OH)-type H-bonding systems, one of the amino hydrogens can be replaced with electron-donating/withdrawing groups. This, together with a versatile capability for modifying the parent moiety, makes feasible the comprehensive spectroscopy and dynamics studies of amino-type excited-state intramolecular proton transfer (ESIPT), which was previously inaccessible in the hydroxyl-type ESIPT systems. Empirical correlations were observed among the hydrogen-bonding strength (the N-H bond distances and proton acidity), ESIPT kinetics, and thermodynamics, demonstrating a trend that the stronger N-H···N hydrogen bond leads to a faster ESIPT, as experimentally observed, and a more exergonic reaction thermodynamics. Accordingly, ESIPT reaction can be harnessed for the first time from a highly endergonic type (i.e., prohibition) toward equilibrium with a measurable ESIPT rate and then to the highly exergonic, ultrafast ESIPT reaction within the same series of amino-type intramolecular H-bond system.

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“…This MOF type is water stable and allows for the incorporation of links of varied nature . Based on ESPT dyes designed by Park et al, the multivariate links are composed of quarterphenyl chains bearing 1,2-diarylphenanthro[9,10- d ]imidazole fluorophores. , This moiety was utilized as a template for its stability to MOF synthetic conditions, high quantum yield, and ease of color variability through synthesis. When the aryl at the 2 position is an o -phenol derivative, the dye can exist as an enol or keto tautomer (Figure d) by transferring the phenolic proton to the unsubstituted nitrogen of the imidazole ring .…”

Section: Introductionmentioning

confidence: 99%

Solid State Multicolor Emission in Substitutional Solid Solutions of Metal–Organic Frameworks

et al. 2019

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Preparing crystalline materials that produce tunable organic-based multicolor emission is a challenge due to the inherent inability to control the packing of organic molecules in the solid state. Utilizing multivariate, high-symmetry metal–organic frameworks, MOFs, as matrices for organic-based substitutional solid solutions allows for the incorporation of multiple fluorophores with different emission profiles into a single material. By combining nonfluorescent links with dilute mixtures of red, green, and blue fluorescent links, we prepared zirconia-type MOFs and found that the bulk materials exhibit features of solution-like fluorescence. Our study found that MOFs with a fluorophore link concentration of around 1 mol % exhibit fluorescence with decreased inner filtering, demonstrated by changes in spectral profiles, increased quantum yields, and lifetime dynamics expected for excited-state proton-transfer emitters. Our findings enabled us to prepare organic-based substitutional solid solutions with tunable chromaticity regulated only by the initial amounts of fluorophores. These materials emit multicolor and white light with high quantum yields (∼2–14%), high color-rendering indices (>93), long shelf life, and superb hydrolytic stability at ambient conditions.

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Synthesis, characterization and optical properties of aryl and diaryl substituted phenanthroimidazoles

Cited by 50 publications

References 80 publications

Insight into the Amino-Type Excited-State Intramolecular Proton Transfer Cycle Using N-Tosyl Derivatives of 2-(2′-Aminophenyl)benzothiazole

Insight into the Amino-Type Excited-State Intramolecular Proton Transfer Cycle Using N-Tosyl Derivatives of 2-(2′-Aminophenyl)benzothiazole

Harnessing Excited-State Intramolecular Proton-Transfer Reaction via a Series of Amino-Type Hydrogen-Bonding Molecules

Solid State Multicolor Emission in Substitutional Solid Solutions of Metal–Organic Frameworks

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