Spectra of 8-hydroxyquinoline

Srivastava, S. L.; Prasad, M.V.S.; Rohitashava,

doi:10.1016/0584-8539(84)80123-3

Cited by 23 publications

(7 citation statements)

References 3 publications

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“…The Raman spectra of the α and β polymorphs of Alq 3 , reported in Figure , clearly reveal three peaks located at 504, 526, and 541 cm -1 for both unsolvated structures. These modes were previously attributed, by comparison with the spectra of naphthalene and quinoxaline, to skeletal in-plane bending of the ligand. , Preliminary ab initio calculations performed on the hydroxyquinoline ligand and the mer isomer of Alq 3 (using the equilibrium molecular geometry obtained from the β structure) confirm the in-plane bending nature of these modes despite the non-strictly-planar geometry of the ligands . Accordingly, since a typical ligand mode is mainly involved in the vibronic structure, we can state the ligand-centered nature of the optically active electronic and vibronic transitions in Alq 3 in agreement with the characteristic fluorogenic character of 8-hydroxyquinoline. , The contribution of other vibrational modes to the vibronic structure cannot be ruled out.…”

Section: Resultsmentioning

confidence: 55%

Correlation between Molecular Packing and Optical Properties in Different Crystalline Polymorphs and Amorphous Thin Films of mer-Tris(8-hydroxyquinoline)aluminum(III)

Brinkmann¹,

Gadret²,

Muccini³

et al. 2000

J. Am. Chem. Soc.

577

515

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Since 1987, high-luminance low-voltage driven devices based on tris(8-hydroxyquinoline)aluminum(III) (Alq 3 ) opened the route to design low-cost large area displays and illuminators. Despite the large number of studies devoted to this material, very little is known about its basic structural and optical properties in the solid state. Therefore, we have investigated the structure(s) and the correlation between intermolecular interactions and optical properties in various Alq 3 systems, including solution, amorphous thin films, and different crystalline forms. Two novel unsolvated polymorphs of Alq 3 , namely, R-Alq 3 and -Alq 3 , have been synthesized and their crystalline structures determined from X-ray diffraction data on powders (R) and single crystals ( ). Crystals of R-Alq 3 are triclinic, space group P-1, a ) 6.2586 (8) Å, b ) 12.914(2) Å; c ) 14.743(2) Å, R ) 109.66(1)°; ) 89.66(1)°, and γ ) 97.68(1)°; crystals of -Alq 3 are triclinic, space group P-1, a ) 8.4433(6) Å, b ) 10.2522(8) Å; c ) 13.1711(10) Å, R ) 108.578(1)°, ) 97.064(1)°, and γ ) 89.743 (1)°. Both these crystal structures consist of a racemic mixture of the mer isomer, but are characterized by different molecular packings involving well-defined short contacts between quinoxaline ligands belonging to symmetry-related Alq 3 molecules with interligand spacings in the 3.5-3.9 Å range. A third "high-temperature" phase, γ-Alq 3 , was found to contain orientationally disordered mer-Alq 3 molecules, lying about a 32 position of the trigonal P-31c space group, with a ) 14.41(1) Å and c ) 6.22(1) Å. In addition, a hemichlorobenzene adduct of Alq 3 was also prepared and structurally characterized (monoclinic, space group P2 1 /n, a ) 10.786(1) Å, b ) 13.808(2) Å, c ) 16.928(2) Å, ) 97.90(2)°). Investigations of the different crystal phases, as well as of amorphous thin films and solutions by absorption, fluorescence excitation, fluorescence, and Raman spectroscopy, allowed the effect of the molecular packing on the emission properties to be elucidated, the nature of the photoexcitations to be clarified, and the vibrational fingerprints of the R and crystalline forms to be highlighted. The spectral position of fluorescence is found to be correlated with both the molecular density of the packing and the length of interligand contacts between neigboring Alq 3 molecules as a consequence of different dispersive and dipolar interactions as well as different π-π orbital overlaps (the shorter the contacts, i.e., the denser the crystal, the more the fluorescence is red-shifted). The low-temperature (4.2 K) vibronic structure of the fluorescence spectrum of Alq 3 is resolved for the first time. It is assigned to the FranckCondon activity of an in-plane bending mode at ca. 525 cm -1 , and it is symptomatic of the ligand-centered nature of the optical transitions. From the analysis of the vibronic progression the existence of a strong electronphonon coupling involving the 525 cm -1 mode with a Huang-Rhys factor of ca. 2.6 ( 0.4 is inferred. The origin of the amorp...

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Section: Resultsmentioning

confidence: 55%

Correlation between Molecular Packing and Optical Properties in Different Crystalline Polymorphs and Amorphous Thin Films of mer-Tris(8-hydroxyquinoline)aluminum(III)

Brinkmann¹,

Gadret²,

Muccini³

et al. 2000

J. Am. Chem. Soc.

577

515

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“…Quinoline belongs to the C s point group. The main vibrations in the 1650−1500 cm -1 spectral range have all been assigned to ring stretching modes having A 1 symmetry. , Out-of-plane vibrations are found only below 1000 cm -1 . In a coordinate system defined as in Figure the ring modes calculated at 1548 and 1618 cm -1 are mainly composed of out-of-phase and in-phase vibrations, respectively, of the C−C bonds parallel to the y -axis.…”

Section: Resultsmentioning

confidence: 94%

“…Theoretical Results and IR Spectra of Cinchonidine, Quinoline, and Quinuclidine. Even though little is reported on the vibrational spectrum of the alkaloid this can be easily related to the spectra of its composing groups, quinoline and quinuclidine (Scheme ). − The 1700−1500 cm -1 spectral region of cinchonidine has been assigned by analogy to the quinoline spectrum. , However, a more detailed analysis of the vibrational modes of the quinoline and quinuclidine moieties is needed here. In particular the direction of the dynamic dipole moment associated with the vibrational modes is important in view of the selection rule for adsorbates on metal surfaces. − Vibrational analysis is restricted here to modes in the 1650−1300 cm -1 spectral region.…”

Section: Resultsmentioning

confidence: 99%

An in Situ Attenuated Total Reflection Infrared Study of a Chiral Catalytic Solid−Liquid Interface: Cinchonidine Adsorption on Pt

2001

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An in situ attenuated total reflection study of the chiral solid-liquid interface created by cinchonidine adsorption on a Pt/Al(2)O(3) model catalyst is presented. Experiments were performed in the presence of dissolved hydrogen, that is under conditions used for the heterogeneous enantioselective hydrogenation of alpha-functionalized ketones. Cinchonidine adsorbs via the quinoline moiety. The adsorption mode is coverage dependent and several species coexist on the surface. At low concentration (10(-6)M) a predominantly flat adsorption mode prevails. At increasing coverage two different tilted species, alpha-H abstracted and N lone pair bonded cinchonidine, are observed. The latter is only weakly bound and in a fast dynamic equilibrium with dissolved cinchonidine. At high concentration (10(-4)-10(-3) M) all three species coexist on the Pt surface. A slow transition from an adsorbate layer with a high fraction of alpha-H abstracted cinchonidine to one with a high fraction of N lone pair bonded cinchonidine is observed with the cinchonidine concentration being the driving force for the process. The reverse transition in the absence of dissolved cinchonidine is fast. Cinchonidine competes with solvent decomposition products for adsorption sites on the Pt, which may contribute to the observed solvent dependence of the heterogeneous enantioselective hydrogenation of ketones by cinchonidine-modified Pt.

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“…8HQ compounds can be applied as chemosensors for ion separation, metal extraction, and preservation in the wood, paper, and textile industry. Moreover, they present agricultural applicability as pesticides, insecticide, and fungicides [2] . With regard to its pharmacological potential, 8HQ has several properties of interest that have been recently revised by Gupta et al.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, they present agricultural applicability as pesticides, insecticide, and fungicides. [2] With regard to its pharmacological potential, 8HQ has several properties of interest that have been recently revised by Gupta et al (2021). [1] 8HQ compounds present activities against bacteria, viruses, fungus, and leishmania, in addition to anti-asthmatic, neuroprotective and anti-cancer actions.…”

Section: Introductionmentioning

confidence: 99%

8‐Hydroxyquinoline, Derivatives and Metal‐Complexes: A Review of Antileukemia Activities

Gasparin

Pilger

2023

ChemistrySelect

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8‐Hydroxyquinoline and its derivatives consist of a group of metal‐binding ligands capable of reaching complexes that present several biological activities. In the present study, we collate and discuss data regarding the antileukemia activities of 8‐hydroxyquinoline (8HQ) compounds to provide an overview of their mechanisms of actions, and a compilation of cytotoxicity data against diverse leukemia cell lines. The pharmacological activities of this class of agents are associated primarily with their ability to coordinate metals and interact with multiple biological targets. We found consistent evidence that 8HQ exerts promising proapoptotic features through its direct interaction with deoxyribonucleic acid (DNA) and inhibition of multiple targets, such as the proteasome, nuclear factor kappa B (NF‐κB), histone deacetylase (HDAC), bromodomain and extra terminal (BET) proteins and janus kinases (JAKs), in addition to inducing autophagy associated cell death. Thus, we provide substantial evidence for the repositioning potential of the 8HQ class for the treatment of leukemia, a hematological malignancy for which urgent advances in therapeutic approaches are needed to overcome conventional therapy limitations.

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Spectra of 8-hydroxyquinoline

Cited by 23 publications

References 3 publications

Correlation between Molecular Packing and Optical Properties in Different Crystalline Polymorphs and Amorphous Thin Films of mer-Tris(8-hydroxyquinoline)aluminum(III)

Correlation between Molecular Packing and Optical Properties in Different Crystalline Polymorphs and Amorphous Thin Films of mer-Tris(8-hydroxyquinoline)aluminum(III)

An in Situ Attenuated Total Reflection Infrared Study of a Chiral Catalytic Solid−Liquid Interface: Cinchonidine Adsorption on Pt

8‐Hydroxyquinoline, Derivatives and Metal‐Complexes: A Review of Antileukemia Activities

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