Vibrational spectroscopic (FT-IR, FT-Raman) studies, Hirshfeld surfaces analysis, and quantum chemical calculations of m-acetotoluidide and m-thioacetotoluidide

Śmiszek-Lindert, Wioleta; Chełmecka, Elżbieta; Góralczyk, Stefan; Kaczmarek, Marian

doi:10.1016/j.molstruc.2016.08.072

Cited by 8 publications

(3 citation statements)

References 28 publications

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“…Below the melting in B, the free N-H stretching at ~3400 cm −1 is absent, whereas it is present in TB even at temperatures below its T g , which is an indication for the weaker association of the thiobarbiturates. While for B, the H-bonded N-H stretching shows a dual peak at 3200 and 3100 cm −1 [ 45 ], denoting the ordered H-bonds in barbiturates, in TB, the H-bonded N-H shows a much broader peak centered at ~3200 cm −1 with weak N-H symmetric stretching at ~3075 cm −1 , indicating a more complex H-bonding pattern due to the existence of the C2=S [ 46 , 47 , 48 ] in the thiobarbiturates. The red-shifted resonance of the C=S band clearly proves that the C2=S is indeed H-bonded with the N-H [ 24 , 47 , 48 , 49 ].…”

Section: Discussionmentioning

confidence: 99%

“…While for B, the H-bonded N-H stretching shows a dual peak at 3200 and 3100 cm −1 [ 45 ], denoting the ordered H-bonds in barbiturates, in TB, the H-bonded N-H shows a much broader peak centered at ~3200 cm −1 with weak N-H symmetric stretching at ~3075 cm −1 , indicating a more complex H-bonding pattern due to the existence of the C2=S [ 46 , 47 , 48 ] in the thiobarbiturates. The red-shifted resonance of the C=S band clearly proves that the C2=S is indeed H-bonded with the N-H [ 24 , 47 , 48 , 49 ]. As temperature rises above 85 °C, B melts partially, showing the free N-H stretching at ~3400 cm −1 , together with a blueshift of the carbonyl stretching from 1692 to 1706 cm −1 , demonstrating that the H-bonds in B are partially broken at elevated temperatures.…”

Section: Discussionmentioning

confidence: 99%

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Comparing C2=O and C2=S Barbiturates: Different Hydrogen-Bonding Patterns of Thiobarbiturates in Solution and the Solid State

Hilgeroth

Hasan

et al. 2021

IJMS

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Carbonyl-centered hydrogen bonds with various strength and geometries are often exploited in materials to embed dynamic and adaptive properties, with the use of thiocarbonyl groups as hydrogen-bonding acceptors remaining only scarcely investigated. We herein report a comparative study of C2=O and C2=S barbiturates in view of their differing hydrogen bonds, using the 5,5-disubstituted barbiturate B and the thiobarbiturate TB as model compounds. Owing to the different hydrogen-bonding strength and geometries of C2=O vs. C2=S, we postulate the formation of different hydrogen-bonding patterns in C2=S in comparison to the C2=O in conventional barbiturates. To study differences in their association in solution, we conducted concentration- and temperature-dependent NMR experiments to compare their association constants, Gibbs free energy of association ∆Gassn., and the coalescence behavior of the N-H‧‧‧S=C bonded assemblies. In Langmuir films, the introduction of C2=S suppressed 2D crystallization when comparing B and TB using Brewster angle microscopy, also revealing a significant deviation in morphology. When embedded into a hydrophobic polymer such as polyisobutylene, a largely different rheological behavior was observed for the barbiturate-bearing PB compared to the thiobarbiturate-bearing PTB polymers, indicative of a stronger hydrogen bonding in the thioanalogue PTB. We therefore prove that H-bonds, when affixed to a polymer, here the thiobarbiturate moieties in PTB, can reinforce the nonpolar PIB matrix even better, thus indicating the formation of stronger H-bonds among the thiobarbiturates in polymers in contrast to the effects observed in solution.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Comparing C2=O and C2=S Barbiturates: Different Hydrogen-Bonding Patterns of Thiobarbiturates in Solution and the Solid State

Hilgeroth

Hasan

et al. 2021

IJMS

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“…The single crystals of (1) and (2) have been obtained by crystallization from a melted substance (melting point of compound (1) and ( 2) is 333K [20] and 338-339K [21], respectively), which appears between two closely CaF 2 windows. The details of the experimental techniques of the preparing and the selection of single crystals from a mosaic are given in References [22][23][24][25][26]. Measurements of the spectra of monocrystalline fragments have been performed for two different orientations of the electric field vector "E" (polarization 0° and 90°).…”

Section: Materials and Physical Measurementsmentioning

confidence: 99%

Towards a better comprehension of interactions in the crystalline N-acetylbenzylamine and its sulphur analogue N-benzyl-ethanethioamide. IR, Raman, DFT studies and Hirshfeld surfaces analysis

Śmiszek-Lindert

Chełmecka

Lindert

et al. 2018

Spectrochimica Acta Part A: Molecular and Biomolecular Spectros

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This paper presents the investigation results of the polarized IR spectra of the hydrogen bond in crystals of N-acetylbenzylamine and its sulphur analogue N-benzyl-ethanethioamide. The spectra were measured at 298 and 77 K by a transmission method, with the use of polarized light. The Raman spectroscopy, Hirshfeld surfaces analysis and DFT studies have been also reported. Theoretical calculations of the isolated molecule were performed by using density functional theory (DFT) method at B3LYP/6-311(d,p), B3LYP/6-311++G(d,p) and B3LYP/6-311++G(3df,2pd) basis set levels. The geometrical parameters of analyzed compounds are in good agreement with the XRD experiment. The vibrational frequencies were calculated and subsequently values have been compared with the experimental Infrared and Raman spectra. It has been shown that the observed and calculated frequencies are found to be in good agreement, as well as the analysis of the Hirshfeld surface has been well correlated to the spectroscopic studies. Additionally, the highest occupied molecular orbital energy (E), lowest unoccupied molecular orbital energy (E), the energy gap between E and E (ΔE), molecular electrostatic potential and global reactivity descriptors viz. chemical potential, global hardness and electrophilicity have been calculated. In N-acetylbenzylamine the presence of the N-benzylamide fragment is essential for activity.

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Theoretical Aspects of Thioamides

Cuevas

García‐Calvo

García-Calvo

et al. 2019

Chemistry of Thioamides

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Vibrational spectroscopic (FT-IR, FT-Raman) studies, Hirshfeld surfaces analysis, and quantum chemical calculations of m-acetotoluidide and m-thioacetotoluidide

Cited by 8 publications

References 28 publications

Comparing C2=O and C2=S Barbiturates: Different Hydrogen-Bonding Patterns of Thiobarbiturates in Solution and the Solid State

Comparing C2=O and C2=S Barbiturates: Different Hydrogen-Bonding Patterns of Thiobarbiturates in Solution and the Solid State

Towards a better comprehension of interactions in the crystalline N-acetylbenzylamine and its sulphur analogue N-benzyl-ethanethioamide. IR, Raman, DFT studies and Hirshfeld surfaces analysis

Theoretical Aspects of Thioamides

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