On the solvatochromism, dimerization and tautomerism of indazole

Catalán, Javier

doi:10.3998/ark.5550190.p008.082

Cited by 3 publications

(3 citation statements)

References 21 publications

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“…Consistent with this hypothesis, for all complexes C2-4 in CH2Cl2, a bi-exponential decay was detected using time-resolved Complex C1 displays a structured emission in CH 2 Cl 2 solution at room temperature (Figure 6a), independent of the excitation wavelength, with three maxima at 440, 466, and 495 nm and a lifetime of 4.2 µs (Figure S53). This luminescence is similar to that recorded in the rigid matrix at 77 K regarding spectral shape and energy, and is compatible with the spectral patterns expected for the phosphorescence of indazole [39]. This evidence indicates that the observed emission in C1 is assignable to phosphorescence from a triplet excited state of LC nature involving the N,N ligand.…”

Section: Emission Studiessupporting

confidence: 86%

“…On the other hand, in the case of complexes C2-4 , the emission spectra at room temperature are generally broad and can be preferentially assigned to phosphorescence from a triplet excited state of MLCT character. Instead, a structured emission is observed at 77 K, akin to complex C1 , whose spectral characteristics point to a triplet LC involving the N , N ligand [ 39 ]. The change in the emitting excited state at room temperature compared to the prototype complex C1 can be associated with the presence of the methyl–ester functional groups.…”

Section: Resultsmentioning

confidence: 99%

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Air- and Water-Stable Heteroleptic Copper (I) Complexes Bearing Bis(indazol-1-yl)methane Ligands: Synthesis, Characterisation, and Computational Studies

Moreno-da Costa,

Zúñiga-Loyola,

Droghetti

et al. 2023

Molecules

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A series of four novel heteroleptic Cu(I) complexes, bearing bis(1H-indazol-1-yl)methane analogues as N,N ligands and DPEPhos as the P,P ligand, were synthesised in high yields under mild conditions and characterised by spectroscopic and spectrometric techniques. In addition, the position of the carboxymethyl substituent in the complexes and its effect on the electrochemical and photophysical behaviour was evaluated. As expected, the homoleptic copper (I) complexes with the N,N ligands showed air instability. In contrast, the obtained heteroleptic complexes were air- and water-stable in solid and solution. All complexes displayed green-yellow luminescence in CH2Cl2 at room temperature due to ligand-centred (LC) phosphorescence in the case of the Cu(I) complex with an unsubstituted N,N ligand and metal-to-ligand charge transfer (MLCT) phosphorescence for the carboxymethyl-substituted complexes. Interestingly, proper substitution of the bis(1H-indazol-1-yl)methane ligand enabled the achievement of a remarkable luminescent yield (2.5%) in solution, showcasing the great potential of this novel class of copper(I) complexes for potential applications in luminescent devices and/or photocatalysis.

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Section: Emission Studiessupporting

confidence: 86%

Section: Resultsmentioning

confidence: 99%

Air- and Water-Stable Heteroleptic Copper (I) Complexes Bearing Bis(indazol-1-yl)methane Ligands: Synthesis, Characterisation, and Computational Studies

Moreno-da Costa,

Zúñiga-Loyola,

Droghetti

et al. 2023

Molecules

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“…A plot of frequency at the maximum of the first absorption band for 5AmMS in 2MB as a function of temperature 19 (Figure 2) revealed that this compound occurs in monomeric form from 293 to 233 K and as clusters below 233 K (probably as a dimer that prevails below 173 K).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Effects of Charge Transfer on the ESIPT Process in Methyl 5-R-Salicylates

Catalán

2014

J. Phys. Chem. B

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The fluorescent behavior of the methyl-5-R-salicylates is analyzed in media of negligible acidity and basicity so that the methyl-5-R-salicylates may undergo solvent dipolarity changes or not in a controlled manner based on the following guidelines: (i) The molecular forms of these methyl-5-R-salicylates possessing an intramolecular hydrogen bond (IMHB) between their hydroxyl group and ether type oxygen (rotated tautomer) undergo no excited-state intramolecular proton transfer (ESIPT) in their first excited electronic state; (ii) on the other hand, the molecular species with an IMHB between its hydroxyl group and carbonyl oxygen (normal tautomer) exhibits both ESIPT and normal emission when charge transfer (CT) from the R-substituent to the phenol group is slight to moderate, but only normal emission is monitored when CT is strong. The special insensitivity of the first UV absorption band for the normal tautomer of methylsalicylate (MS, with R = H) to the polarity of the solvent is not echoed by the normal forms of methyl-5-R-salicylates containing substituents R with a substantial effect of CT in the IMHB of the compound. These solvatochromic features of MS are shared by the emissions of its derivatives. The photophysical evidence found for the methyl-5-R-salicylates confirms the photophysical model recently reported (Phys. Chem. Chem. Phys. 2012, 14, 8903-8909), which assigns three fluorescent emissions to the methyl-5-R-salicylates: two of them coming from the IMHB normal tautomer, which undergoes ESIPT, and another from the IMHB rotated tautomer, which cannot undergo ESIPT.

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Picosecond excited-state lifetimes of protonated indazole and benzimidazole: The role of the N–N bond

Marlton

McKinnon

Greißel

et al. 2021

The Journal of Chemical Physics

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Certain chemical groups give rise to characteristic excited-state deactivation mechanisms. Here, we target the role of a protonated N–N chemical group in the excited-state deactivation of protonated indazole by comparison to its isomer that lacks this group, protonated benzimidazole. Gas-phase protonated indazole and protonated benzimidazole ions are investigated at room temperature using picosecond laser pump–probe photodissociation experiments in a linear ion-trap. Excited state lifetimes are measured across a range of pump energies (4.0–5.4 eV). The 1ππ* lifetimes of protonated indazole range from 390 ± 70 ps using 4.0 eV pump energy to ≤18 ps using 4.6 eV pump energy. The 1ππ* lifetimes of protonated benzimidazole are systematically longer, ranging from 3700 ± 1100 ps at 4.6 eV pump energy to 400 ± 200 ps at 5.4 eV. Based on these experimental results and accompanying quantum chemical calculations and potential energy surfaces, the shorter lifetimes of protonated indazole are attributed to πσ* state mediated elongation of the protonated N–N bond.

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On the solvatochromism, dimerization and tautomerism of indazole

Cited by 3 publications

References 21 publications

Air- and Water-Stable Heteroleptic Copper (I) Complexes Bearing Bis(indazol-1-yl)methane Ligands: Synthesis, Characterisation, and Computational Studies

Air- and Water-Stable Heteroleptic Copper (I) Complexes Bearing Bis(indazol-1-yl)methane Ligands: Synthesis, Characterisation, and Computational Studies

Effects of Charge Transfer on the ESIPT Process in Methyl 5-R-Salicylates

Picosecond excited-state lifetimes of protonated indazole and benzimidazole: The role of the N–N bond

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