Presence of π…π and C H…π interactions in the new Schiff base 2-{( E )-[(3- tert -butyl-1-phenyl-1 H -pyrazol-5-yl)imino]methyl}phenol: Experimental and DFT computational studies

Abstract

This version is available at https://strathprints.strath.ac.uk/61820/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the Strathprints administrator: strathprints@strath.ac.ukThe Strathprints institutional repository (https://strathprints.strath.ac.uk) is a digital archive of University of Strathclyde research outputs. It has been developed to disseminate open access research outputs, expose data about those outputs, and enable the management and persistent access to Strathclyde's intellectual output. Presence of ... and C-H new Schiff base 2-{(E)-[(3-tertbutyl-1-phenyl-1H-pyrazol-5-yl)imino]methyl}phenol: Experimental and DFT ABSTRACTA combined theoretical and experimental study on the structure, infrared and UV-Vis data of 2-, is presented. Theoretical geometry optimization and its IR spectrum were carried out using the Density Functional Theory (DFT), while for the theoretical UV-Vis spectrum, the Time-Dependent DFT (TD-DFT) method was used. The supramolecular analysis of the compound evidenced the presence o C-Hinteractions between the methyl group and the phenyl rings which form chains of molecules parallel to the plane (100).

Synthesis and Characterization of New Bases Derived from Nitrophenylpyrazoles, Coordination to Palladium and Antifungal Activity and Catalytic Activity in Mizoroki–Heck Reactions

“…The IR spectra of compounds 7-10 each showed an intense band in the 3455-3326 cm −1 range assigned to the OH group, and for compounds 3-6, these bands were in the 3450-3419 cm −1 range. These observations for compounds 3-6 are consistent with the presence of an intramolecular hydrogen bond between the phenolic H atom and the imine N atom [52][53][54][55]. Additional bands in the IR spectra of Schiff bases 3-10 were assigned on the basis of spectra of analogous compounds [52,53,56]: (i) the band between 3141-3120 cm −1 was assigned to the H-C= stretching of the pyrazole; (ii) the band between 3095-3022 cm −1 was assigned to the C-H stretching of the aromatic rings; (iii) the band between 2968-2954 cm −1 was assigned to the asymmetric stretching of the C-H aliphatic tertbutyl groups (symmetric stretching at 2871-2861 cm −1 ); (iv) the band at 1623-1596 cm −1 was assigned to the -C=N vibration of the imine groups; (v) the band at 1535-1511 cm −1 was assigned to the asymmetric stretching of the -NO 2 group (1357-1334 cm −1 for the symmetric stretching; see Figures S4-S6, Supplementary Materials).…”

“…For compounds 4-6 and 8-10, which have the nitro group on the aromatic ring, in the MS, the fragmentation pattern is characteristic of the six compounds, with a base peak corresponding to the molecular ion [M] + (364 m/z). The MS of compounds 3 and 7 show base peaks corresponding to their [M-CH 3 ] + ions (304 m/z, 100) as previously shown for this class of compounds [52][53][54], as well as a peak for the molecular ion [M] + (319 m/z, 83.43). The MS spectra of the Schiff bases are shown in Figures S1-S3 (Supplementary Material).…”

“…The values obtained for compounds 3-10 and the energy differences of the FMOs are shown in Table 2. The values in the Table 2 for compounds 3 and 6 were taken from references [52][53][54].…”

Synthesis, Structural Characterization, and In Vitro and In Silico Antifungal Evaluation of Azo-Azomethine Pyrazoles (PhN2(PhOH)CHN(C3N2(CH3)3)PhR, R = H or NO2)

“…The experimental and calculated UV-Vis spectra of compounds Azo1 to Azo4 are presented in Figure 5, whereas the respective log ε value, excitation energy, and orbital contributions for each absorption are shown in Table S1 in Supplementary Materials. All compounds presented an experimental absorption band around 234 nm that is consistent with a typical π→π* transition in aromatic compounds [24][25][26]28]. Theoretical calculations indicate that this band is associated with the transition HOMO→LUMO+4 (77%, logε 4.461), HOMO→LUMO+3 (26%, logε 4.623), HOMO-3→LUMO+3 (79%, logε 4.715), and HOMO-1→LUMO+6 (78%, logε 5.051) for compounds Azo1 to Azo4, respectively, which is further associated with the pyrazole and the phenyl rings [1].…”

“…Due to the effective antifungal activity detected both for azomethine compounds containing pyrazole rings substituted with nitrated aromatics and for their azo derivatives [19][20][21][22], we have decided to design new Schiff bases constructed by assembling azo fragments functionalized with aromatic groups and aromatic pyrazoles substituted in ortho, meta or para positions by nitro groups. Therefore, this study has resulted in the synthesis, structural characterization (XRD, GC-MS, NMR, IR, and UV-Vis), and antifungal evaluation of four novel azo-pyrazole-azomethines with the general formula R-(PhOH)-(H)C=N-((C 3 HN 2 )(tert-butyl)(R')) with R = Ph-N=N-and R = Ph-or -Ph-NO 2 in the search for new azomethine Schiff bases derivatives [23,24]. Biological tests were performed against certified strains of Candida albicans (ATCC 10231) and Cryptococcus neoformans (ATCC 32264).…”