INTRAMOLECULAR HYDROGEN BONDING AND THE ANHARMONICITY OF THE NH2 STRETCHING VIBRATIONS IN SUBSTITUTED ANILINES

The fundamental and first overtone NH2 stretching bands in 55 ortho-, meta-, and para-substituted anilines, measured in dilute carbon tetrachloride solution, have been compared. For all ortho-substituted compounds (except o-alkyl, o-COCH3, and o-COOCH2CH3) splitting of the symmetric band is observed in the first overtone region. On the basis of unusually low mechanical anharmonicity the high-frequency component is assigned to a vibration arising in an intramolecularly bonded NH2 group. The mechanical anharmonicity of the "free" NH2 group is found to be more dependent on the electronic nature of meta and para substituents for the symmetric mode than for the asymmetric mode, with minor changes on ortho substitution. The relative electrical anharmonicities for both modes have been estimated from changes in the ratio of the integrated intensity of the fundamental band to that of the first overtone band. For the asymmetric mode the electrical anharmonicity is independent of the electronic nature of the substituents, but depends on their ring position. For the symmetric mode the electrical anharmonicity decreases as charge separation increases in the molecule, with no significant difference for ortho-substituted compounds. These results are in qualitative agreement with a mechanism previously proposed for these vibrations.

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Autonomic Conditions in Tinnitus and Implications for Korean Medicine

Evidence-based Complementary and Alternative Medicine ◽

10.1155/2013/402585 ◽

2013 ◽

Vol 2013 ◽

pp. 1-5 ◽

Cited By ~ 6

Author(s):

Eun Ji Choi ◽

Younghee Yun ◽

Seungyeon Yoo ◽

Kyu Seok Kim ◽

Jeong-Su Park ◽

...

Keyword(s):

High Frequency ◽

Low Frequency ◽

Retrospective Chart Review ◽

Frequency Component ◽

Total Power ◽

High Frequency Component ◽

Chronic Patients ◽

Research Attention ◽

Korean Medicine ◽

Significant Difference

Tinnitus patients suffer from not only auditory sensations but also physical, mental, and social difficulties. Even though tinnitus is believed to be associated with the autonomic nervous system, changes in autonomic conditions in tinnitus patients are not receiving much research attention. The aims of this study were to investigate the autonomic condition of tinnitus patients and to consider Korean medicine in the treatment of tinnitus with an evidence-based approach. We performed a retrospective chart review and compared the heart rate variability (HRV) parameters of 40 tinnitus patients (19 acute and 21 chronic) and 40 healthy controls. In tinnitus patients, the power of the high frequency component and total power of the HRV significantly decreased(P<0.05), and the low frequency to high frequency ratio significantly increased(P<0.05). There was no significant difference between the acute and chronic patients. When comparing each group with the controls, there was a tendency that the longer the duration of tinnitus was, the larger the observed HRV change was. In conclusion, tinnitus patients have vagal withdrawal and sympathetic overactivity, and chronic tinnitus more strongly affects autonomic conditions than acute tinnitus. This study provides evidence for Korean medical treatments of tinnitus, such as acupuncture and Qi-training, that cause modulation of cardiac autonomic function.

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Aromatic amides. V. Intramolecular hydrogen bonding in ortho-substituted anilides

Australian Journal of Chemistry ◽

10.1071/ch9701667 ◽

1970 ◽

Vol 23 (8) ◽

pp. 1667 ◽

Cited By ~ 13

Author(s):

JM Appleton ◽

BD Andrews ◽

ID Rae ◽

BE Reichert

Keyword(s):

Hydrogen Bonding ◽

Molecular Geometry ◽

Intramolecular Hydrogen Bonding ◽

Amide Group ◽

Amide Proton ◽

Substituted Anilines ◽

Real Value ◽

Intramolecular Hydrogen ◽

Acyl Derivatives ◽

Ortho Substituent

The proton magnetic resonance spectra of deuterochloroform solutions of a number of ortho-substituted anilines and their S-acyl derivatives have been measured. Variations in the acylation shifts of the ring protons are explained in terms of intramolecular hydrogen bonding between the amide proton and the ortho-substituent. Calculations of the contribution made to the acylation shifts by the anisotropy of the amide group were found to be too sensitive to the molecular geometry to be of any real value. Acylation shifts for a series of 4'-substituted 2'-nitroacetanilides correlate well with the σp values of the 4'-substituents.

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The Female Heart: Sex Differences in the Dynamics of ECG in Response to Stress

10.1101/368845 ◽

2018 ◽

Author(s):

Tricia Adjei ◽

Jingwen Xue ◽

Danilo P. Mandic

Keyword(s):

Sex Differences ◽

Stress Response ◽

Pilot Study ◽

Mental Stress ◽

Stress Hormones ◽

Frequency Component ◽

Sample Entropy ◽

High Frequency Component ◽

P Value ◽

Significant Difference

AbstractSex differences in the study of the human physiological response to mental stress are often erroneously ignored. To this end, we set out to show that our understanding of the stress response is fundamentally altered once sex differences are taken into account. This is achieved by comparing the heart rate variability (HRV) signals acquired during mental maths tests from ten females and ten males of similar maths ability; all females were in the follicular phase of their menstrual cycle. For rigour, the HRV signals from this pilot study were analysed using temporal, spectral and nonlinear signal processing techniques, which all revealed significant statistical differences between the sexes, with the stress-induced increases in the heart rates from the males being significantly larger than those from the females (p-value=2.2×10−3). In addition, mental stress produced an overall increase in the power of the low frequency component of HRV in the males, but caused an overall decrease in the females. The stress-induced changes in the power of the high frequency component were even more profound; it greatly decreased in the males, but increased in the females. We also show that mental stress was followed by the expected decrease in sample entropy, a nonlinear measure of signal regularity, computed from the males’ HRV signals, while overall, stress manifested in an increase in the sample entropy computed from the females’ HRV signals. This finding is significant, since mental stress is commonly understood to be manifested in the decreased entropy of HRV signals, however, the significant difference (p-value=2×10−9) in the changes in the entropies from the males and females highlights the pitfalls in ignoring sex in the formation of a physiological hypothesis. Furthermore, it has been argued that oestrogen attenuates the effect of catecholamine stress hormones; the findings from this investigation suggest for the first time that the conventionally cited cardiac changes, attributed to the fight-or-flight stress response, are not universally applicable to females. Instead, this pilot study provides an alternative interpretation of cardiac responses to stress in females, which indicates a closer alignment to the evolutionary tend-and-befriend response.

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The assessment of intramolecular hydrogen bonding in ortho-substituted anilines by an NMR method

Journal of Molecular Liquids ◽

10.1016/j.molliq.2020.113730 ◽

2020 ◽

Vol 315 ◽

pp. 113730

Author(s):

Michael H. Abraham ◽

Raymond J. Abraham ◽

Amin Aghamohammadi ◽

Kamyar Afarinkia ◽

Xiangli Liu

Keyword(s):

Hydrogen Bonding ◽

Intramolecular Hydrogen Bonding ◽

Substituted Anilines ◽

Nmr Method ◽

Intramolecular Hydrogen

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DOUBLE-MINIMUM POTENTIAL FOR INTRAMOLECULARLY HYDROGEN-BONDED PROTONS IN ORTHO-SUBSTITUTED ANILINES

Canadian Journal of Chemistry ◽

10.1139/v64-038 ◽

1964 ◽

Vol 42 (2) ◽

pp. 201-211 ◽

Cited By ~ 19

Author(s):

P. J. Krueger

Keyword(s):

Hydrogen Bonding ◽

Vibrational Level ◽

Fundamental Mode ◽

Intramolecular Hydrogen Bonding ◽

Antisymmetric Mode ◽

Substituted Anilines ◽

Minimum Potential ◽

Intramolecular Hydrogen ◽

Ortho Substituent ◽

Hydrogen Bonded

The concentration and temperature-independent splitting of the first overtone NH2 symmetric stretching band in 31 ortho-substituted anilines in which intramolecular hydrogen bonding is possible is interpreted in terms of a double-minimum potential for the hydrogen bonded proton. The intensity ratio of the doublet and the extent of the splitting is related to the basicity of the ortho-substituent, modified by the rigid geometrical restrictions of the intramolecular system. The absence of band splitting in the corresponding fundamental mode suggests that the secondary minimum lies in the vicinity of the v = 2 vibrational level. The antisymmetric mode appears to be less sensitive to perturbations.Deuteration studies, the spectra of some o-substituted N-methyl anilines, and the first over-tone bands of N-methyl aniline in very basic solvents support these views.

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THE VIBRATIONAL MECHANISM OF THE FUNDAMENTAL NH2 STRETCHING VIBRATIONS IN ANILINES

Canadian Journal of Chemistry ◽

10.1139/v62-354 ◽

1962 ◽

Vol 40 (12) ◽

pp. 2300-2316 ◽

Cited By ~ 70

Author(s):

Peter J. Krueger

Keyword(s):

Lone Pair ◽

Intramolecular Hydrogen Bonding ◽

Electronic Effects ◽

Substituted Anilines ◽

Tetrahedral Configuration ◽

Nitrogen Lone Pair ◽

Resultant Increase ◽

Stretching Vibrations ◽

Integrated Intensities ◽

Intramolecular Hydrogen

The integrated intensities, frequencies, and half-band widths of the fundamental symmetric and asymmetric NH2 stretching vibrations in 33 ortho-substituted anilines, measured in dilute carbon tetrachloride solution, have been examined in relation to the corresponding absorption band parameters for 31 meta- and para-substituted anilines, taking into consideration the electronic effects of the substituents. From an almost tetrahedral configuration in p-phenylenediamine, the calculated s-character of the nitrogen atom gradually increases as the substituent groups become more electron withdrawing, with a resultant increase in the apparent HNH angle and the NH force constant. Ortho substitution in general leads to enhanced HNH angle opening, probably because of intramolecular hydrogen bonding. The decrease in half-band width for both vibrational modes in ortho-substituted anilines with respect to corresponding values in meta and para compounds is ascribed to steric hindrance to solvation of the amino group.The asymmetric intensities in ortho-substituted anilines are generally increased over corresponding values in meta and para compounds, unlike the behavior of the symmetric mode. These results are consistent with a vibrational mechanism taking into account the following factors for each mode: (i) the direction of the transition moment, (ii) the extent of nitrogen lone pair and aromatic π-electron participation, and (iii) the direct field effect of the ortho substituent.

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Two solvatomorphic forms of a copper complex formulated as Cu(L1)(ClO4)2·1.2H2O and Cu(L1)(ClO4)2, whereL1is 3,10-C-meso-3,5,7,7,10,12,14,14-octamethyl-1,4,8,11-tetraazacyclotetradecane

Acta Crystallographica Section C Crystal Structure Communications ◽

10.1107/s0108270113013711 ◽

2013 ◽

Vol 69 (7) ◽

pp. 689-695 ◽

Cited By ~ 4

Author(s):

Babul Chandra Nath ◽

Sebastián Suarez ◽

Fabio Doctorovich ◽

Tapashi G. Roy ◽

Ricardo Baggio

Keyword(s):

Hydrogen Bonding ◽

Copper Complex ◽

Intramolecular Hydrogen Bonding ◽

Molecular Shape ◽

Octahedral Environment ◽

Significant Difference ◽

Intramolecular Hydrogen

Two copper complex solvatomorphs, namely (3,10-C-meso-3,5,7,7,10,12,14,14-octamethyl-1,4,8,11-tetraazacyclotetradecane)bis(perchlorato-κO)copper(II) 1.2-hydrate, [Cu(ClO4)2(C18H40N4)]·1.2H2O, (I), and (3,10-C-meso-3,5,7,7,10,12,14,14-octamethyl-1,4,8,11-tetraazacyclotetradecane)bis(perchlorato-κO)copper(II), [Cu(ClO4)2(C18H40N4)], (II), are described and compared with each other and with a third, already reported, anhydrous diastereomer, denoted (III). Both compounds present very similar centrosymmetic coordination environments, with the CuIIcation lying on an inversion centre in a distorted 4+2 octahedral environment, defined by the macrocyclic N4group in the equatorial sites and two perchlorate groups intrans-axial positions [one of the perchlorate ligands in (I) is partially disordered]. The most significant difference in molecular shape is seen in the orientation of the perchlorate anions, and the influence of this on the intramolecular hydrogen bonding is discussed. The (partially) hydrated state of (I) favours the formation of chains along [011], while the anhydrous character of (II) and (III) promotes loosely bound structures with low packing indices.

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