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Structural optimization, molecular docking analysis, electronic and vibrational properties have been investigated for the 1-benzofuran-2-carboxylic acid (2BF) and 1-benzofuran-3-carboxylic acid (3BF) using DFT/B3LYP/6-311++G(d,p) level of theory. The theoretical parameters have a very good consistency with the experimental ones. The weak intermolecular interactions were analyzed by different tool such as: Hirshfeld surfaces, topological analysis and natural bond orbital studies. The nonlinear optical properties have been investigated. Molecular electrostatic potential and frontier molecular orbitals (FMOs) analysis have been carried out to understand the reactivity of the molecule. In addition, TD-DFT calculation is initiated to simulate the UV-vis absorption spectrum and to determine several important electronic properties like HOMO-LUMO gap energy and electronic transitions. The complete vibrational assignments and the force constants were reported for monomer and dimers of both acids. The biological activities of the tow acids have been studied via molecular docking analysis. The later calculations prove that the studied acids have an inhibitor effect against cancer and microbial diseases.

Oxindole (indolin-2-one, Ox) is a unique and a crucial molecular system in spectroscopic studies. Indole is the core structure of many substances found in the human body (tryptophan, serotonin) and the indole alkaloids have highly differentiated pharmacological properties such as analgesic, anti-fever and anti-inflammatory. The Ox's structural results given in the Cambridge Structural Database revealed the existence of only one crystalline form of Ox, referred to the α-form. However, we have experimentally noticed the existence of two polymorphic forms during the crystallization of Ox. Furthermore, the significant spectral differences that we have observed in the solid state infrared spectra of these two forms additionally confirm the existence of the polymorphism phenomenon. Of the four polymorphic forms of Ox, two of them – α - and β-forms – were of particular interest. In the crystalline lattices of both polymorphs, we observed a similar pattern of molecular arrangements giving rise to the supramolecular synthon according to the terminology of Etter. Moreover, hydrogen bonds in the dimer of the α-form are found to be non-equivalent (non-centrosymmetric dimers), having a length of 2797 A and 2979 A, respectively. Comparatively, in the most densely packed crystalline structure of Ox, the β-form, the dimer is formed by a pair of almost identical intermolecular hydrogen bonds and consequently the crystals of β-form exhibited spectral properties typical to centrosymmetric hydrogen bond dimers. In addition, the spectroscopic studies that we have conducted to polymorphic forms of Ox, isotopically diluted with deuterium, show the dramatic influence of isotopic substitution in the hydrogen bridge on the infrared spectra of hydrogen bonding. Thus, the main goal of this work is the proposition of a theoretical approach that can describe the main features of the crystalline infrared spectra of the Ox polymorphs. The proposed approach is based on the phenomenon of the exciton coupling results directly from intermolecular interactions in the vibrationally excited state which leads to the delocalization of the excitation over the molecules in the lattice and to the Davydov splitting effect in the crystalline spectra.

This paper deals with the experimental and theoretical studies of abnormal properties of terephthalic acid (TAC) and phthalic acid (PAC) crystals manifested in the H/D isotopic exchange. The widely utilized deuteration routine appeared to be insufficiently effective in the case of the h 6 -TAC isotopomer. In the case of the d 4 -TAC derivative the isotopic exchange process occurred noticeably more effectively. In contrast, both isotopomers of PAC, h 6 and d 4 , appeared much more susceptible for deuteration. A theoretical model was elaborated describing “long-distance” dynamical co-operative interactions involving hydrogen bonds in TAC and PAC crystals. The model assumes extremely strong dynamical co-operative interactions of hydrogen bonds from the adjacent (COOH) 2 cycles. This leads to an additional stabilization of h 6 –TAC molecular chains. The interaction energies affect the chemical equilibrium of the H/D isotopic exchange. The model predicts a differentiated influence of the H and D atoms linked to the aromatic rings on to the process. In this approach the totally-symmetric C H bond stretching vibrations and the proton stretching totally symmetric vibrations couple with the π -electronic motions. It was also shown that identical hydrogen isotope atoms, H or D, in whole TAC molecules, noticeably enlarge the energy of the dynamical co-operative interactions in the crystals, in contrast to the case of different hydrogen isotopes present in the carboxyl groups and linked to the aromatic rings. The “long-distance” dynamical co-operative interactions in PAC crystals were found of a minor importance due to the electronic properties of PAC molecules.

Deep tissue abscesses remain a significant cause of morbidity, mortality, and hospital stay despite improved surgical techniques and use of perioperative antibiotics. Long-term antibiotics increase risk of acquired resistance and polymicrobial infection, limiting future treatment options. We have therefore undertaken a Phase 1 clinical trial to evaluate safety and feasibility of methylene blue mediated photodynamic therapy (MB-PDT) at the time of drainage to treat deep tissue abscesses. This trial uses a fixed photosensitizer dose (1 mg/mL) delivered directly to the abscess cavity, and escalates light dose using a 3+3 design. Three patients were treated at the lowest light dose (20 mW/cm2, 6 J/cm2), with no study-related adverse events. Based on the technical success of this group, recruitment will continue for higher light dose groups with relaxed inclusion criteria. This trial restricts potential subjects to those with single abscesses less than 8 cm in diameter. To investigate MB-PDT feasibility in a wider population, we extracted CT images for patients receiving abscess drainage locally. Images were segmented and imported into a custom Monte Carlo simulation framework. Simulations were performed to determine whether 20 mW/cm2 could be delivered to 95% of the abscess wall, given the available 2 W of optical power at the treatment fiber output. Preliminary results show that this is achievable in 80% of abscesses examined, with volumes ranging from 30-250 mL. Optical power required ranged from 50-950 mW. Based on these initial results, it appears that a large number of abscesses drained may be candidates for MB-PDT.

Over the last decades, several approaches have been developed for elucidating the infrared spectral density of dicarboxylic acid crystals, which has been served as prototype for determining hydrogen bonds dynamics. These approaches differ in how accurately the simulated spectra can superimpose the experimental ones. In this study, we present a superdimer quantum approach susceptible to elucidate the infrared spectral properties of some particular dicarboxylic acid crystals using a newly proposed algorithm, which favors the rule of Davydov coupling in the generation of the spectra. The approach, which is herein effectively applied to terephthalic and phthalic acid dimer crystals, ascribes the non-conventional IR spectral properties of these particular acid crystals to the existence of superdimer structure in their lattices. In this superdimer structure, a strong vibronic coupling mechanism, namely Davydov coupling, takes place between the proton stretching vibrations in the (COOH)₂ cycles. This strong coupling exciton, generated by the resonance arising in the two coupled (COOH)₂ cycles of the aromatic rings of the superdimer, in conjunction with the strong anharmonic coupling between the fast and slow modes of each hydrogen bonds provide a strong support basis for a common explanation of the physical properties of these two different crystalline systems. The numerical simulations, involving the implications of the superdimer model, are systematically correlated with the experimental spectra. A decent agreement between the evaluated spectra and the experimental bandshapes of terephthalic and phthalic dicarboxylic acid crystals was obtained using a set of physically sound parameters as inputs in the theoretical formulation. The superdimer quantum approach thereby underscore the potential of the dynamical cooperative interactions between “Davydov coupling” and “strong anharmonic coupling” mechanisms in the generation of the spectral features of terephthalic and phthalic dicarboxylic acid crystals, suggesting that the congregated effects of these two mechanisms can be considered as the most reliable source of the non-conventional IR spectral properties observed. It is therefore expected that this novel algorithm reduces the discrepancies between the simulated spectra compared to the experimental one and simplify the computation of spectra in more complex hydrogen bonded systems.

The present treatment shows that the lichen family Trypetheliaceae is an important component of lowland and montane tropical forests in Bolivia. A total of 75 species are currently recognized in Bolivia, of which 24 are new to science and a further 37 are reported for the first time from the country. The following species are described: Architrypethelium penuriixanthum Flakus & Aptroot sp. nov. that differs from A. hyalinum in the lack of lichexanthone in the thallus; Astrothelium amylosporum Flakus & Aptroot sp. nov. that differs from A. subdisjunctum in having 8-spored asci and amyloid ascospores; A. bullatum Flakus & Aptroot sp. nov. that differs from A. megaspermum in having a bullate thallus, a clear hamathecium, 8-spored asci and smaller amyloid ascospores; A. carrascoense Flakus, Kukwa & Aptroot sp. nov. that differs from A. meristosporum in having broader ascospores without distinctly thickened median septa, an unidentified xanthone as major substance, and mostly eccentric ostioles; A. elixii Flakus & Aptroot sp. nov. that differs from all other Astrothelium species in the presence of lichexanthone in the outer layer of thallus and pseudostromata and isohypocrellin inside the pseudostromata, and muriform ascospores; A. inspersotuberculosum Flakus & Aptroot sp. nov. that differs from A. tuberculosum in having an inspersed hamathecium; A. megaeneum Flakus & Aptroot sp. nov. that differs from A. croceum in having a thallus covered by parietin, and mostly fused ascomata with intermediate, fused to separated ostioles surrounded by a common ostiolar area; A. neodiplocarpum Flakus, Kukwa & Aptroot sp. nov. that differs from A. diplocarpum in the absence of medullary pigment and in the amyloid ascospores; A. nigrocacuminum Flakus, Kukwa & Aptroot sp. nov. that differs from A. megochroleucum in having fused, eccentric ostioles and black (UV−) tops of the pseudostromata; A. pallidoflavum Flakus & Aptroot sp. nov. that differs from A. cinnamomeum in having wider ascospores; A. pyrenuliforme Flakus & Aptroot sp. nov. that differs from A. ecuadoriensis ecuadoriense in having shorter ascospores and in the presence of pseudocyphellae; A. subscoria Flakus & Aptroot sp. nov. that differs from A. scoria in having non-aggregated ascomata; A. variabile Flakus & Aptroot sp. nov. that differs from A. ochroleucoides in the longer ascospores; Bathelium boliviense Flakus & Aptroot sp. nov. that differs from B. lineare in the presence of isohypocrellin inside the pseudostromata; B. flavostiolatum Flakus & Aptroot sp. nov. that differs from all other Bathelium species in the presence of lichexanthone near the ostioles (tops of pseudostromata UV+ yellow) and an orange (K+ carmine red) pigment inside the pseudostromata, the absence of lichexanthone in the thallus, an inspersed hamathecium, and 13–17-septate ascospores; B. inspersomastoideum Flakus & Aptroot sp. nov. that differs from B. mastoideum in having an inspersed hamathecium; B. mirabile Flakus, Kukwa & Aptroot sp. nov. that differs from other Bathelium species in the pseudostromata containing isohypocrellin inside and parietin outside; B. pruinosum Flakus, Kukwa & Aptroot sp. nov. that differs from Astrothelium ochroleucoides in having 8-spored asci, shorter ascospores, an inspersed hamathecium, and an unidentified anthraquinone (orange pigment K+ carmine red) inside the pseudostromata; Constrictolumina chiquitana Flakus, Kukwa & Aptroot sp. nov. that differs from other known Constrictolumina species in having brown and 1-septate to submuriform ascospores; Dictyomeridium lueckingii Flakus & Aptroot sp. nov. that differs from D. proponens in having smaller and less septate ascospores; Polymeridium xanthoexcentricum Flakus & Aptroot sp. nov. that differs from P. alboflavescens in having mostly eccentric ostioles; Pseudopyrenula flavosuperans Flakus & Aptroot sp. nov. that differs from P. superans in having a hamathecium inspersed with yellow oil globules; Trypethelium astroideum Flakus & Aptroot sp. nov. that differs from T. subeluteriae in having K+ carmine red pseudostromata containing parietin inside and black tops with an additional unidentified anthraquinone (rust-red pigment K+ purple, UV−) on the outside, partly fused ostioles, and larger ascospores; and T. xanthoplatystomum Flakus & Aptroot sp. nov. that differs from T. platystomum in the presence of lichexanthone in the thallus.

The approach of deriving new photoresponsive active supramolecular azopolymers based on the hydrogen bonds is described. Polymers with imide rings, i.e., poly(esterimide)s and poly(etherimide)s, with phenolic hydroxyl or carboxylic groups were applied as matrixes for the polymer–dye supramolecular systems. Supramolecular films were built on the basis of the hydrogen bonds between the functional groups of the polymers and various azochromophores, that is, 4-phenylazophenol, 4-[4-(6-hydroxyhexyloxy)phenylazo]benzene, 4-[4-(6-hexadecaneoxy)phenylazo]pyridine and 4-(4-hydroxyphenylazo)pyridine. The hydrogen bonding interaction in azo-systems were studied by Fourier transform infrared spectroscopy and for selected assembles by 1H NMR technique. The obtained polyimide azo-assembles were characterized by X-ray diffraction and DSC measurements. H-bonds allow attaching a chromophore to each repeating unit of the polymer, thereby suppressing the macroscopic phase separation except for the systems based on 4-[4-(6-hydroxyhexyloxy)phenylazo]benzene. H-bonds systems were amorphous and revealed glass transition temperatures lower than for the polyimide matrixes (170–260 °C). The photoresponsive behavior of the azo-assemblies was tasted in holographic recording experiment.

This letter is devoted to the explanation of the differences between the IR spectral properties of hydrogen bond systems found in crystals of two isomeric thioamides, thioacetanilide (TACN) and N-methylthiobenzamide (NMTB). The magnitude of the temperature-dependent Davydov-splitting effects, the H/D isotopic ‘ self - organization ’ effects in the crystalline polarized IR spectra depend on the electronic properties of the two different associating molecular systems, which are affected by the methyl and phenyl substituent groups linked to the H N C S common structural fragments.

Monocrystals of the 3-thiopheneacetic and 3-thiopheneacrylic acid dimers were investigated by polarized IR spectroscopy at 77 and 293 K in the υO‒H and υO‒D band frequency ranges. We propose to elucidate the strong difference between spectra of the two individual systems, expressed by the corresponding band shapes and by the temperature effects characterizing the bands. The experimental results are compared to predictions obtained with theoretical calculations based on a model for a centrosymmetric hydrogen-bonded dimer that treats the high-frequency OH stretches harmonically and the low-frequency intermonomer stretches anharmonically. It was found that the vibronic coupling mechanism involving the hydrogen bond protons and the electrons on the π-electronic systems in the molecules determines the way in which the vibrational exciton coupling between the hydrogen bonds in the carboxylic acid dimers occurs.

In this work, the molecular structures and vibrational spectral analyses of 3-(2-Theinyl)acrylic acid (3-2TAA) monomer and dimer structures have been reported by using density functional theory calculations at B3LYP/6-311++G(d,p) level of theory. The complete assignments of the fundamental vibrational modes were obtained using potential energy distribution. Intermolecular interactions were analyzed by orbital NBO and topological AIM approaches. The electronic properties have been carried out using TD-DFT approach. Great agreements between experimental and theoretical values were achieved throughout the analysis of structural parameters and spectroscopic features. Inhibitor characteristics on human monoamine oxidase B (MAOB) enzyme of two determined stable conformers of 3-2TAA (β and γ) along with four selective inhibitors, namely safinamide, a coumarin analogue, farnesol, and phenyethylhydrazine were investigated via molecular docking. Moreover, molecular electrostatic potential (MEP) and temperature dependency of thermodynamic functions have been reported. © 2016 Elsevier B.V.

Polarized IR spectra were recorded in the spectral range of the νN–H and νN–D proton stretching vibration bands for the isotopically neat and isotopically diluted crystals of pyrazole (Pzl) and quinolin-2(1H)-one (2HQ). The spectra measured in the temperature range of 77–293 K have shown that temperature extremely strongly influenced the magnitude of the Davydow-splitting effects in the crystalline spectra. Two different competing vibrational Davydow-coupling mechanisms involving hydrogen bonds, i.e., the ‘tail-to-head’ and the ‘side-to-side’, were responsible for the generation of the temperature effects in the polarized spectra.

The structural and vibrational properties of cyclic dimer of 2-furoic acid (2FA) were predicted by combining the available experimental infrared and Raman spectra in the solid phase and ab initio calculations based on density functional theory (DFT) with Pople's basis sets. The calculations show that there are two cyclic dimers for the title molecule that have been theoretically determined in the gas phase, and that only one of them, cis conformer, is present in the solid phase. The complete assignment of the 66 normal vibrational modes for the cis cyclic dimer was performed using the Pulay's Scaled Quantum Mechanics Force Field (SQMFF) methodology. Four strong bands in the infrared spectrum at 1583, 1427, 1126 and 887 cm(-1) and the group of bands in the Raman spectrum at 1464, 1452, 1147, 1030, 885, 873, 848, 715 and 590 cm(-1) are characteristic of the dimeric form of 2FA in the solid phase. In this work, the calculated structural and vibrational properties of both dimeric species were analyzed and compared between them. In addition, three types of atomic charges, bond orders, possible charge transfer, topological properties of the furan rings, Natural Bond Orbital (NBO) and Atoms in Molecules (AIM) theory calculations were employed to study the stabilities and intermolecular interactions of the both dimers of 2FA.

Polarized IR spectra of 2-furanacetic acid and of 2-furanacrylic acid crystals were measured at 293 K and 77 K in the vO−H and vO−H band frequency ranges. The corresponding spectra of the two individual systems strongly differ, one from the other, by the corresponding band shapes as well as by the temperature effect characterizing the bands. The crystal spectral properties remain in a close relation with the electronic structure of the two different molecular systems. We show that a vibronic coupling mechanism involving the hydrogen bond protons and the electrons on the π-electronic systems in the molecules determines the way in which the vibrational exciton coupling between the hydrogen bonds in the carboxylic acid dimers occurs. A strong coupling in 2-furanacrylic acid dimers prefers a “tail-to-head-” type Davydov coupling widespread by the π-electrons. A weak through-space coupling in 2-furanacetic acid dimers is responsible for a “side-to-side-” type coupling. The relative contribution of each exciton coupling mechanism in the dimer spectra generation is temperature and the molecular electronic structure dependent. This explains the observed difference in the temperature-induced evolution of the compared spectra.

Two new secondary Mannich bases, 4-bromo-2-[(aminopropyl)methyl]-phenol (1) and 4-nitro-2-[(aminopropyl)methyl]-phenol (2), were synthesized. Crystal structures were determined at liquid nitrogen temperature. It was found that in both compounds the proton transfer forms exist in the solid state. In the case of 1, this was unexpected, because of the weak acidity of p-bromophenol being the parent component of this Mannich base. The reason for that was found to be the formation of the O–···H–N+ hydrogen bonded tetramer in the solid state. Two cyclic aggregates R42(8) and R22(12) describe the pattern of hydrogen bonded interactions in the crystals of both compounds. Additionally, C–H···π interactions stabilize the crystal structures. The hydrogen bonds in 1are slightly stronger (N···O distances 2.708 and 2.733 A) than in 2 (2.721 and 2.765 A, respectively) despite the fact that p-nitrophenol participating in 2 is a stronger acid. The influence of permittivity of surroundings and the hydrogen bonding pattern o...

It is shown that the resonance of the O-H and C-H bond stretching vibrations is responsible for a noticeable intensity redistribution effect in the IR spectra of associated formic acid molecules in the gaseous phase. This effect is manifested by a considerably high growth in intensity of the νC-H band, which overlaps the νO-H band contour in the spectra. A vibronic coupling of the Herzberg-Teller-type expressed by the second order term in the perturbation theory is the most probable source of these spectral effects. The presented mechanism explains the variation of the effect magnitude accompanying the phase transitions. The proposed model also facilitates the understanding of the H/D isotopic effects in the spectra as well as the essential difference in the corresponding spectral properties between the formic and the acetic acid.

This paper explains the problem of the fair similarity of the ν O–H band contour shapes in the spectra of liquid and crystal samples of hydrogen-bonded acetic acid, in contrast to the corresponding spectral properties of formic acid. It has been proven that regardless of the relative arrangement of hydrogen bonds in each phase, the hydrogen-bonded dimeric systems decide about the profile of the bands. Moreover, the model dimers of different symmetry, i.e., the C i or C 2v one of the “ side-to - side ” type arrangement of moieties, yield nearly identical spectra. Qualitatively similar spectral properties in the ν O–D band frequency range were found for deuterium-bonded formic and acetic acid isotopologues.

This paper presents the investigation results of the polarized IR spectra of the hydrogen bond in crystals of 3- and 4-methylthioacetanilide. The spectra were measured at 293 and 77 K by a transmission method, with the use of polarized light. The main spectral properties of the crystals can be interpreted satisfactorily in terms of the "strong-coupling" theory, on the basis of the hydrogen bond centrosymmetric dimer model. The spectra revealed that the strongest vibrational exciton coupling involved the closely spaced hydrogen bonds, each belonging to a different chain of associated 3- and 4-methylthioacetanilide molecules. A weaker exciton coupling involved the adjacent hydrogen bonds in each individual chain. It was proven that a nonrandom distribution of the protons and deuterons took place in the lattices of isotopically diluted crystalline samples of 3- and 4-methylthioacetanilide. In each case, the H/D isotopic "self-organization" mechanism involved all four hydrogen bonds from each unit cell.

This paper presents the results of experimental studies of hydrogen-bonded 2-pyridone crystal IR spectra. Spectral studies have demonstrated the existence of two anhydrous solid-state phases of each compound, namely the α and the β phases. Hydrogen bonds in the high-temperature α phase of these crystals have been estimated to be 40% stronger than the hydrogen bonds in the β phase, which are stable at room temperature. The mechanism of the phase transition in the solid-state 2-pyridone is proposed on the basis of the IR spectral data. This was possible by taking into account small changes in the geometry of heterocyclic molecular skeletons, which accompany the electron density redistribution in the hydrogen bonds occurring during the transition. The phase transition is connected with a partial change in the hydrogen bond nature from the N(+)-H···O(-) in the α phase, to the N-H···O hydrogen bonds in the β phase crystals.

This paper presents the investigation results of the polarized IR spectra of 3-hydroxybenzaldehyde and 4-hydroxybenzaldehyde crystals measured at 293 and 77 K. Analysis of the results concerned the linear dichroic, H/D isotopic and temperature effects observed in the spectra of the hydrogen and deuterium bond at the frequency ranges of the ν O–H and the ν O–D bands, respectively. The main spectral properties of the crystals were interpreted in terms of the “ strong - coupling ” theory on the basis of the hydrogen bond dimer model. The spectra revealed that the strongest vibrational exciton coupling involved the closely-spaced hydrogen bonds, each belonging to a different chain of associated molecules. The reason for two different crystalline systems, are characterized by almost identical ν O–H and ν O–D band shapes, is explained. It was proved that a random distribution of the protons and deuterons took place in the lattices of the isotopically diluted crystals.

This Article presents the investigation results of the polarized IR spectra of the hydrogen bond in acetanilide (ACN) crystals measured in the frequency range of the proton and deuteron stretching vibration bands, nu(N-H) and nu(N-D). The basic spectral properties of the crystals were interpreted quantitatively in terms of the "strong-coupling" theory. The model of the centrosymmetric dimer of hydrogen bonds postulated by us facilitated the explanation of the well-developed, two-branch structure of the nu(N-H) and nu(N-D) bands as well as the isotopic dilution effects in the spectra. On the basis of the linear dichroic and temperature effects in the polarized IR spectra of ACN crystals, the H/D isotopic "self-organization" effects were revealed. A nonrandom distribution of hydrogen isotope atoms (H or D) in the lattice was deduced from the spectra of isotopically diluted ACN crystals. It was also determined that identical hydrogen isotope atoms occupy both hydrogen bonds in the dimeric systems, where each hydrogen bond belongs to a different chain. A more complex fine structure pattern of nu(N-H) and nu(N-D) bands in ACN spectra in comparison with the spectra of other secondary amides (e.g., N-methylacetamide) can be explained in terms of the "relaxation" theory of the IR spectra of hydrogen-bonded systems.

Polarized IR spectra of the hydrogen bond in 2-thiophenic acid crystals, isotopically neat and of mixed H/D isotopic content, are measured at 298 and 77 K in the "residual" nuO-H and nuO-D band frequency ranges. This crystalline system provides spectra in these band frequency ranges that differ considerably in intensity distribution from the spectra of other H-bonded centrosymmetric dimeric species. This change in the spectral properties of the crystals is probably due to the influence of the sulfur atoms from the thiophene aromatic rings, which are directly linked to the (COOH)2 or (COOD)2 cycles. The magnitude of this effect correlates with the net electronic charge distribution at the 2- and 3-positions of substituted thiophene rings, which in a different way influences the electron charge density in the hydrogen bonds of the two thiophenic acid isomers. The experimental results for spectral structures are compared to predictions obtained with theoretical calculations involving the combined effects of anharmonicities, Davydov coupling, Fermi resonances, and direct and indirect relaxations within the framework of the linear response theory. Numerical results show that mixing of all these effects allows satisfactory reproduction of the main features of the experimental IR line shapes of crystalline H- and D-bonded 2-thiophenic acid at room and liquid-nitrogen temperatures.

This paper presents the results of the re-investigation of polarized IR spectra of adipic acid and of its d 2 , d 8 and d 10 deuterium derivative crystals. The spectra were measured at 77 K by a transmission method using polarized light for two different crystalline faces. Theoretical analysis concerned linear dichroic effects and H/D isotopic effects observed in the spectra of the hydrogen and deuterium bonds in adipic acid crystals at the frequency ranges of the ν O–H and the ν O–D bands. The two-branch fine structure pattern of the ν O–H and ν O–D bands and the basic linear dichroic effects characterizing them were ascribed to the vibronic mechanism of vibrational dipole selection rule breaking for IR transitions in centrosymmetric hydrogen bond dimers. It was proved that for isotopically diluted crystalline samples of adipic acid, a non-random distribution of protons and deuterons occurs in the dimers (H/D isotopic “ self-organization ” effect). This effect results from the dynamical co-operative interactions involving the dimeric hydrogen bonds.

The polarized IR spectra of the hydrogen bond systems were studied in crystals of 2-furancarboxylic acid C 4 H 3 O–COOH as well as in crystals of its deuterium-bonded derivative. The spectra were measured by a transmission method at room temperature and at 77 K. Theoretical analysis of the results concerned the linear dichroic effects, the H/D isotopic and the temperature effects observed in the solid-state IR spectra at the frequency ranges of the ν O–H and the ν O–D bands, respectively. The main spectral properties of the crystals can be quantitatively interpreted in terms of the “ strong-coupling ” theory for a hydrogen bond dimer model. This model explains satisfactorily not only the two-branch structure of the ν O–H and the ν O–D bands, the temperature-induced evolution of the crystalline spectra, but also the basic linear dichroic effects observed in the band frequency ranges. A vibronic mechanism, responsible for promotion of the symmetry-forbidden transition in the IR and for the excitation of the totally symmetric proton stretching vibrations in centrosymmetric hydrogen bond dimers was also taken into the account. An excess of fine linear dichroic effects, accompanying the splitting of the spectral lines in the crystalline spectra, appeared for the crystal with only one dimer in a unit cell. This fact suggests that the existence of a specific co-operative interaction effect in the lattice, depending on the stimulated rearrangement of the proton positions in the hydrogen bond dimers, occurring in the nearest surrounding of an individual dimer in the lattice. Therefore, regardless of the published X-ray P 1 ¯ space-symmetry of the lattice, the effective unit cell for explaining the crystalline spectra behaved as if it contained two nonequivalent dimers. Re-examination of the crystal X-ray structure supported the hypothesis concerning the lattice transformation predicted by the IR spectroscopic studies.

This article presents the investigation results of polarized IR spectra of the hydrogen bond in N -methylacetamide (NMA) crystals measured in the frequency range of the proton and deuteron stretching vibration bands, ν N–H and ν N–D . A similar study was also performed for crystals of the deuterium isotopomers of the compound, D 7 -NMA (CD 3 CONDCD 3 ) and D 6 -NMA (CD 3 CONHCD 3 ). On the basis of the analysis of the linear dichroic and temperature effects, the two-branch structure of the ν N–H bands in the spectra was ascribed to centrosymmetric hydrogen bond pairs in the lattice. Each hydrogen bond in such a dimeric system belonged to another chain of the associated molecules. The exciton interactions involving the dimer hydrogen bonds were considered to be responsible for the band shape generation. For the deuterium-bonded crystals the exciton interactions were found to be weaker since the ν N–D bands were less split. Within an individual hydrogen or deuterium bond chain the in-chain exciton couplings involving hydrogen bonds were estimated as considerably weaker than the inter-chain ones. The exciton dilution retains the two-branch fine structure pattern of the “ residual ” ν N–H and ν N–D bands. This means that the inter-chain couplings involving hydrogen bonds do not change, when the in-chain couplings vanish. These results are the evidence of the influence of non-conventional co-operative interactions occurring in the hydrogen bond systems on the spectra. These co-operative interactions are responsible for the non-random distribution of the hydrogen isotope atoms in the hydrogen bridge lattices, namely for the grouping of identical hydrogen isotope atoms in the dimers. The proposed interpretation of the IR spectra of the hydrogen bond in N -methylacetamide (NMA) crystals casts light on the spectra generation mechanisms and gives a new meaning to the traditional nomenclature applied for describing the ν N–H band structure pattern in IR spectra of amides.

A simple two step method for the preparation of graft copolymers is described in this paper. For the synthesis of the prepolymers the alkoxyaminemonomers 2-methyl-acryli-acid-4-[1-(2,2,6,6-tetramethyl-piperidine-1-yloxy)ethyl]-benzylester(Mas-BzEt-TEMPO) and 2-methyl-acrylic-acid-4-{1-[N-tert-butyl-N-(1-isopropyl-2-methyl-propyl)-amino-oxy]ethyl}-benzylester (Mas-BzEt-BIPNO) were utilized in radical copolymerizations with styrene, methylmethacrylate, butylmethacrylate and n-butylacrylate. These copolymers were then used as multifunctional macroinitiators for nitroxide mediated graft polymerization of styrene and n-butylacrylate. The polymerizations were carried out in bulk at 125 °C.

In this article, we present the results of our study of polarized IR spectra of the hydrogen bond in crystals of 2-butynoic acid (CH3C CCOOH) as well as in crystals of its deuterium derivative (CH3C CCOOD). 2-Butynoic acid can exist in two polymorphous crystalline forms: in the “α” form, based on a classic dimer motif and in the “β” form, based on the catamer pattern of the hydrogen bond arrangement. By cooling the melted substance crystals of the “β” phase were obtained selectively. The polarized IR spectra of the hydrogen bond in the “β” form of 2-butynoic acid crystals were measured at room temperature and at the temperature of liquid nitrogen in the νO–H and νO–D band frequency ranges. In terms of the “strong-coupling” theory the fine structure patterns of the νO–H and νO–D polarized bands were quantitatively explained along with the dichroic and the H/D isotopic effects in the spectra. To interpret the main properties of the spectra the existence of a non-conventional effect concerning a self-stimulated concerted proton position rearrangements in the neighboring cells in the lattice had to be assumed. On the basis of the spectra of isotopically diluted crystalline samples of 2-butynoic acid it was suggested that a random distribution of protons and deuterons occurred in the open chains of the hydrogen bonded molecules. However, coordination in the mutual arrangement of protons and deuterons in the neighboring hydrogen bonds from the closely spaced molecular chains was found to be non-random. This fact was ascribed to dynamical co-operative interactions, most strongly involving hydrogen bonds from different chains in the modified lattice. These non-conventional interactions were responsible for appearance of the so-called H/D “self-organization” isotopic effects in the spectra.

A suitable method to synthesize well defined polymers with different architectures is the application of functionalized alkoxyamines in the controlled radical polymerization. The analysis of such nitroxide capped polymers by MALDI-TOF-MS is complex. Unexpected results of the mass analysis of our polymers lead us to study the influence of the structure of the analyte and the experimental conditions of the measurements in detail. In addition to common nitroxides like TEMPO, TEMPO-derivates, TIPNO and BIPNO, other alkoxyamines with special structure requirements were synthesized. These alkoxyamines were tested in different MALDI experiments. Supported by a comparison with other methods we postulate a fragmentation mechanism inside the nitroxide-group which takes place during the MALDI measurement. To the best of our knowledge such a fragmentation of the nitroxide-group itself during a MALDI-TOF experiment has not been described before.

The paper presents the results of our investigations of the polarized IR spectra of the hydrogen bond in crystals of acetic acid, CH3COOH, as well as in crystals of three deuterium isotopomers of the compound: CH3COOD, CD3COOH and CD3COOD. The spectra were measured at 283 K and at 77 K by a transmission method using polarized light. Theoretical analysis of the results concerned the linear dichroic effects, together with the H/D isotopic and temperature effects observed in the solid-state IR spectra of the hydrogen and of the deuterium bond at the frequency ranges of the νO–H and the νO–D bands, respectively. Basic spectral properties of the crystals can be interpreted satisfactorily in terms of one of the quantitative theories of the IR spectra of the hydrogen bond, i.e. the “strong-coupling” theory or the “relaxation” theory when a hydrogen bond dimer model is used. From the spectra obtained it resulted that the strongest exciton coupling involved the closely spaced hydrogen bonds, belonging to different chains of associated acetic acid molecules. These results contradict the former explanation of the spectra within a model, which assumed a strong vibrational exciton coupling between four hydrogen bonds in a unit cell. On analyzing the spectra of isotopically diluted crystalline samples of acetic acid it has been proved that a non-random distribution of the protons and deuterons takes place in the hydrogen bond lattices. This non-conventional isotopic effect is a result of dynamical co-operative interactions involving hydrogen bonds in the system. Simultaneously it has been also found that in an individual hydrogen bonded chain in the crystals, distribution of the hydrogen isotope atoms H and D was fully random. The H/D isotopic “self-organization” mechanism most probably involves a pair of hydrogen bonds from each unit cell where each hydrogen bond belongs to a different chain.

This paper presents the results of our investigation of the polarized IR spectra of the hydrogen bond in crystals of 3-hydroxy-4-methyl-2(3H)-thiazolethione. These spectra were measured at room temperature and at 77 K by a transmission method using polarized light. The spectral studies were preceded by re-determination of the crystal X-ray structure. Theoretical analysis of the results concerned linear dichroic effects, the H/D isotopic and temperature effects observed in the solid-state IR spectra of hydrogen and deuterium bonds at frequency ranges of the νO H and the νO D bands, respectively. Basic spectral properties of the crystals can be interpreted satisfactorily in terms of the “strong-coupling” theory, when based on a hydrogen bond dimer model. This model sufficiently explains not only the two-branch structure of the νO H and the νO D bands and the temperature-induced evolution of the crystalline spectra, but also the linear dichroic effects observed in the band frequency ranges. A vibronic mechanism responsible for promotion of the symmetry forbidden transition in the IR for the totally symmetric proton stretching vibrations in centrosymmetric hydrogen bond dimers was analyzed. The crystal spectral properties were successfully interpreted on assuming a “reversal” Davydow-splitting effect expressed by changing of the vibrational exciton interaction energy sign for hydrogen bond dimers in the lattice. These effects were ascribed to a considerable elongation of the dimeric O H ⋯ S bonds in the crystal due to the large atomic radius of sulfur determining the dimer geometry.

In this paper, we present the results of our investigation of the polarized IR spectra of the hydrogen bond in formic acid crystals, as well as in crystals of the three deuterium derivatives of the compound: DCOOH, HCOOD, and DCOOD. These spectra were measured by a transmission method, using polarized light at 273 K and also at the temperature of liquid nitrogen for the “ bc ” crystalline face. Our studies mainly focused on spectral effects corresponding to the intensity distribution, the influence of temperature, the linear dichroism, and isotopic substitution of deuterium in formic acid molecules measured in the frequency range of the proton and the deuterium stretching vibration bands, ν O–H and ν O–D , respectively. The basic spectral properties of the hydrogen bond IR spectra of formic acid crystals were interpreted in a quantitative way in terms of the “strong-coupling” theory. On the basis of this theoretical model, we succeeded in explaining the fine structure patterns of the ν O–H and ν O–D polarized sub-bands, the temperature, the dichroic, and the H/D isotopic effects in the spectra. The spectra were interpreted as a result of vibrational exciton interactions involving two adjacent hydrogen bonds in one chain of the associated molecules. The hydrogen bonds from one unit cell belonging to different chains were found uncoupled. In the spectra of isotopically diluted crystalline samples of HCOOH and DCOOH we found no characteristic changes in the “residual” ν O–H band shapes, which could be attributed to a random distribution of protons and deuterons in open chains of the hydrogen bonded molecules. This fact proves the existence of strong dynamical co-operative interactions in the hydrogen bond chain system in the formic acid crystal lattices responsible for a non-random distribution of protons and deuterons in the chains.

We have investigated the polarized IR spectra of the hydrogen bond system in crystals of trans-styrylacetic acid C(6)H(5)CHCHCH(2)COOH, and also in crystals of the following three deuterium isotopomers of the compound: C(6)H(5)CHCHCH(2)COOD, C(6)H(5)CHCHCD(2)COOH and C(6)H(5)CHCHCD(2)COOD. The spectra were measured at room temperature and at 77K by a transmission method. The spectral studies were preceded by determination of the X-ray crystal structure. Theoretical analysis of the results concerned linear dichroic effects, the H/D isotopic and temperature effects, observed in the solid-state IR spectra of the hydrogen and of the deuterium bond, at the frequency ranges of the nu(OH) and the nu(OD) bands, respectively. Basic spectral properties of the crystals can be interpreted satisfactorily in terms of the "strong-coupling" theory, when based on a hydrogen bond dimer model. This model sufficiently explained not only a two-branch structure of the nu(OH) and the nu(OD) bands, and temperature-induced evolution of the crystalline spectra, but also the linear dichroic effects observed in the band frequency ranges. A vibronic mechanism was analyzed, responsible for promotion of the symmetry-forbidden transition in the IR for the totally symmetric proton stretching vibrations in centrosymmetric hydrogen bond dimers. It was found to be of minor importance, when compared with analogous spectral properties of arylcarboxylic acid, or of cinnamic acid crystals. These effects were ascribed to a substantial weakening of electronic couplings between the hydrogen bonds of the associated carboxyl groups and the styryl radicals, associated with the separation of these groups in styrylacetic acid molecules by methylene groups in the molecules.

The synthesis of the new α-hydrogen bearing nitroxide, 2,2,5-trimethyl-4-(isopropyl)-3-azahexane-3-oxyl (BIPNO) (4), and its corresponding alkoxyamine, N-tert-butyl-N-(1-isopropyl-2-methyl-propyl)-O-(1-phenyl-ethyl)-hydroxylamine (PhEt-BIPNO) (7), are described in this paper. Reaction of styrene with the new nitroxide in the presence of a Jacobsen-like manganese catalyst, Mn(salen)Cl, at ambient atmosphere afforded the alkoxyamine in 96% yield. Styrene and n-butyl acrylate were polymerized in bulk in the presence of the new alkoxyamine. The alkoxyamine turned out to be a suitable initiator for controlled radical polymerization.

This paper presents the results of our investigation with the polarized IR spectra of the hydrogen bond in the 3-pyridinealdoxime and 4-pyridnealdoxime crystals, and also in the crystals of the deuterium derivatives of these two compounds. In each case these spectra were measured for the two different crystalline faces at room temperature and at 77 K by a transmission method, using the polarized light. Theoretical analysis of the results concerned linear dichroic effects, and the H/D isotopic and temperature effects, observed in the solid-state IR spectra of the hydrogen and the deuterium bond, at the frequency ranges of the ν O–H and the ν O–D bands. Basic spectral properties of the crystals can be interpreted in a satisfactory quantitative way for a hydrogen bond linear dimer model in terms of the ‘ strong-coupling ’ theory. This model explains not only a two-branch structure of the ν O–H and the ν O–D bands in the crystalline spectra, but also some essential linear dichroic effects in the band frequency ranges, for isotopically diluted crystals. Within the scope of our studies, the mechanism of the H/D isotopic self-organization processes (which take place in the crystalline hydrogen bond lattices) was also recognized. It was proved that for isotopically diluted crystalline samples of 3-pyridinealdoxime and 4-pyridnealdoxime, a non-random distribution of the protons and deuterons occurs exclusively in some restricted fragments (i.e. domains) of open chains of the hydrogen bonded molecules. Nevertheless, these co-operative interactions between the hydrogen bonds do not concern the adjacent fragments of the neighboring hydrogen bond chains in the lattice. The electronic structure of these compounds was considered as responsible for such co-operative effects of the hydrogen bonds.

This paper presents the investigation results of the polarized IR spectra of H1245 imidazole crystals and of D1H245, D1245 and H1D245 imidazole deuterium derivative crystals. The spectra were measured using polarized light at the room temperature and at 77 K by a transmission method, for two different crystalline faces. Theoretical analysis of the results concerned linear dichroic effects, H/D isotopic and temperature effects, observed in the spectra of the hydrogen and of the deuterium bonds in imidazole crystals, at the frequency ranges of ν N–H and ν N–D bands. The basic crystal spectral properties can be satisfactorily interpreted in a quantitative way for a hydrogen bond linear dimer model. Such a model explains not only a two-branch structure of the ν N–H and ν N–D bands in crystalline spectra, but also some essential linear dichroic effects in the band frequency ranges, for isotopically diluted crystals. Model calculations, performed within the limits of the strong-coupling model, allowed for quantitative interpretation and for understanding of the basic properties of the hydrogen bond IR spectra of imidazole crystals, H/D isotopic, temperature and dichroic effects included. The results allowed verification of theoretical models proposed recently for the imidazole crystal spectra generation mechanisms. In the scope of our studies, the mechanism of H/D isotopic self-organization processes, taking place in the crystal hydrogen bond lattices, was also recognized. It was proved that for isotopically diluted crystalline samples of imidazole, a non-random distribution of protons and deuterons exclusively occurs in some restricted fragments (domains) of open chains of the hydrogen-bonded molecules. Nevertheless, these co-operative interactions between the hydrogen bonds do not concern adjacent fragments of neighboring hydrogen bond chains in the lattice. Analysis of the isotopic self-organization effects in the spectra of imidazole crystals delivered crucial arguments for understanding of the nature of the hydrogen bond spectra generation mechanisms.

This paper presents the results of investigation of the polarized IR spectra of cinnamic acid and of its deuterium derivative crystals. The spectra were measured by a transmission method, using polarized light, at the room temperature and at 77 K, for two different crystalline faces. Theoretical analysis of the results concerned linear dichroic effects, H/D isotopic and temperature effects, observed in the spectra of the hydrogen and of the deuterium bonds in cinnamic acid crystals, at the frequency ranges of the ν O–H and the ν O–D bands. The basic crystal spectral properties could be satisfactorily interpreted in a quantitative way for a centrosymmetric cyclic hydrogen bond dimer model. Such a model explains not only a two-branch structure of the ν O–H and ν O–D bands in crystalline spectra, but also some essential linear dichroic effects in the band frequency ranges, measured for isotopically diluted crystals. Model calculations, performed within the limits of the ‘strong-coupling’ model, allowed for quantitative interpretation and for understanding of the basic properties of the hydrogen bond IR spectra of cinnamic acid crystals, H/D isotopic, temperature and dichroic effects included. In the scope of our studies the mechanism of H/D isotopic ‘self-organization’ processes, taking place in the crystal hydrogen bond lattices, was also recognized. It was proved that for isotopically diluted crystalline samples of cinnamic acid, a non-random distribution of protons and deuterons occurs exclusively in the hydrogen bond dimers. Nevertheless, these co-operative interactions between the hydrogen bonds do not involve the adjacent hydrogen bond dimers in each unit cell. The two-branch fine structure pattern of the ν O–H and ν O–D bands was ascribed to the vibronic mechanism of vibrational dipole selection rule breaking in centrosymmetric hydrogen bond dimers. The observed in the spectra very high intensity of the forbidden transition sub-band in the analyzed ν O–H and ν O–D bands is a manifestation of an extremely effective symmetry rule breaking mechanism. It correlates with a relatively large excess electron charge on the cinnamic aid dimer carboxyl groups. This effect is a result of a partial withdrawal of the electron charge, from the conjugated π-bond systems of the styryl substituents, by the carboxyl groups. This statement has been supported by ab initio calculations.

This paper deals with experimental studies and with the quantitative interpretation of the polarized IR crystalline spectra of 1-naphthylacetic and 2-naphthylacetic acid. The spectra were measured in the ν O–H and in the ν O–D band frequency ranges, at the temperatures of 298 and 77 K. The intensity distribution in the bands was quantitatively reproduced on the basis of the strong-coupling model, when assuming that the isolated (COOH) 2 and (COOD) 2 cycles were the source of the spectral properties of the crystals. Such approach appeared to be sufficient for explaining most of the isotopic and the temperature effects in the spectra. A vibronic mechanism, promoting the symmetry forbidden transition in the IR, for the totally symmetric proton stretching vibrations in centrosymmetric hydrogen bond dimers, was found to be of a considerably minor importance, when compared with analogous spectral properties of arylcarboxylic acid crystals. Also no Fermi resonance impact on the ν O–H band shape was identified in the 1-naphthylacetic and 2-naphthylacetic acid crystal spectra. These effects were ascribed to weakening of electronic couplings between the hydrogen bonds and the phenyl rings, due to the separation of these molecular fragments by methylene groups in 1-naphthylacetic and 2-naphthylacetic acid molecules.

Chlorine-functionalized TEMPO-capped polystyrenes were investigated using the matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) technique. Amine- and acrylate-functionalized agents and bifunctional TEMPO-capped polystyrene were also analyzed to demonstrate the applicability of this method. Using this technique allowed to analyze the conversion of the chlorine function to an acrylate function, which was previously difficult to detect with other methods.

In this paper a theoretical model has been proposed aiming to explain a new kind of H/D isotopic effects, i.e. the isotopic ‘self-organization’ effects, recently deduced from IR spectra of hydrogen bonded molecular crystals. The existence of the new kind of co-operative effects in cyclic dimeric systems of hydrogen bonds was explained in the limits of a vibronic model in the Herzberg–Teller approximation, which assumed a strong coupling between the proton stretching vibrations in a dimer with the electronic motions. It was shown that additional ‘attracting’ forces, responsible for an additional stabilization energy of a dimer, concerning identical hydrogen isotope atoms, appear in the ground vibrational and the ground electronic state, when the proton totally symmetric vibrations in a dimer couple with the electronic movement. These self-organization effects were deduced to be absent in the case of non-symmetric ‘HD’ -type dimers, containing both X–H⋯Y and X–D⋯Y bonds in one dimer. Therefore, the symmetric dimers of the ‘HH’ and the ‘DD’ -type should be more stable when compared with the ‘HD’ -type dimer properties. This would explain characteristic spectral effects, registered in the spectra of partially deuterated molecular crystals containing cyclic dimers of hydrogen bonds in their lattices, depending on a fair invariance of the proton ‘residual’ ν X–H bands in their IR spectra.

This paper deals with experimental studies and with quantitative interpretation of the polarized IR crystalline spectra of phenylacetic acid and of its deuterium isotopomers d2 and d7. The spectra were measured in the v(O-H) and in the v(O-D) band frequency ranges at temperatures of 298 and 77 K. The intensity distribution in the bands was quantitatively reproduced on the basis of the strong-coupling model, when assuming that the isolated (COOH)2 and (COOD)2 cycles were the source of the spectral properties of the crystals. Such approach appeared to be sufficient for explaining most of the isotopic and the temperature effects in the spectra. A vibronic mechanism, promoting the symmetry forbidden transition in the IR for the totally symmetric proton stretching vibrations in centrosymmetric hydrogen bond dimers, was found to be of a considerably minor importance, when compared with analogous properties of arylcarboxylic acid crystals. The spectra of phenylacetic acid crystals, unlike the spectra of arylacetic acid crystals do not exhibit the so-called H/D long-range isotopic effects, depending on an influence of the aromatic ring hydrogen atoms on the v(O-H) band fine structure patterns. Also no Fermi resonance impact on the v(O-H) band shape was identified in the phenylacetic acid crystal spectra. These effects were ascribed to weakening of electronic couplings between the hydrogen bonds and the phenyl rings, due to the separation of these groups in phenylacetic acid molecules by methylene groups.

We have studied the polarized IR spectra of the hydrogen-bonded molecular crystals of 2-hydroxybenzothiazole (HBT) and 2-mercaptobenzothiazole (MBT). The crystal structure of 2-hydroxybenzothiazole was determined by X-ray diffraction. The polarized spectra of the crystals were measured, in the frequency ranges of the νN–H and νN–D bands, at room temperature, and at 77 K. In both systems an extremely strong H/D isotopic effect in the spectra was observed, involving reduction of the well-developed νN–H band fine structure to a single prominent νN–D line only. The two νN–H bands were also shown to exhibit almost identical properties, band shapes, temperature and dichroic properties included. The spectra were quantitatively reconstituted, along with the strong isotopic effect, when calculated using the ‘strong-coupling’ theory, assuming the centrosymmetric dimers of HBT or MBT to be the structural units responsible for the crystalline spectral properties. The similarity of the spectra of the two crystalline systems was considered to be a result of longer-distance couplings between the proton vibrations in the dimers, via the aromatic ring electrons. When investigating the ‘residual’ νN–H band shapes for crystals isotopically diluted by deuterium, we observed some ‘self-organization’ effects in the spectra, indicating the energetically favored presence of two identical hydrogen isotopes in each hydrogen bond dimer.

In this work, molecular geometries and fundamental vibrational frequencies of 2-furanacetic acid (2FAA) and its hydrogen bonded dimer were investigated using DFT/B3LYP method with 6-311++G(d,p) as basis set. The FT-infrared and FT-Raman spectra of the 2FAA compound were recorded in the region 4000–400 cm −1 . The theoretical wavenumbers were scaled and compared with experimental FT-IR and FT-Raman spectra. Complete vibrational assignments and analysis of the fundamental modes of monomer and dimer structures were performed on the basis of the potential energy distribution (PED) calculations. A study on the electronic properties, such as excitation energies, oscillator strength, wavelengths, HOMO and LUMO energies, are performed by time-dependent DFT (TD-DFT) approach. Molecular stability arising from hyperconjugative interactions and charge delocalization has been analyzed using Natural Bond Orbital (NBO) analysis. Topological parameters such an electron density and its Laplacian at bond critical points (BCP) of O H and O⋯H contact bonds were analyzed in details with the help of the atoms in molecules (AIM) approach in order to study the intermolecular hydrogen bonding. The nonlinear optical properties of the title molecule have been investigated. Moreover, molecular electrostatic potential (MEP) surface was plotted for predicting sites and relative reactivities towards electrophilic and nucleophilic attack. The nonlinear optical properties were reported and compared with that of the urea. The thermodynamic properties like heat capacity, entropy, and enthalpy have been calculated for the molecule at different temperatures.

The spectral properties of four different crystalline succinic acid (HOOC-(CH2)2-COOH) (SAC) isotopomer systems, h6, d2, d4 and d6, were examined by means of the IR spectroscopy in polarized light aided by numerical simulations of the νO–H and νO–D band contour shapes on utilizing the “strong-coupling” model. The abnormal IR spectral properties of SAC crystals in relation to the corresponding properties of glutaric, pimelic and adipic acid crystals were ascribed to the hyperconjugation electronic effects in the acid associated molecules. A vibronic coupling mechanism involving the proton stretching vibrations in the (COOH)2 cycles and the electronic motions in the molecular skeletons, the isotopic “H/D self-organization” mechanisms and a long-distance vibrational exciton coupling between the adjacent (COOH)2 cycles in the molecular chains are mainly responsible for the generation of the temperature effects in the crystalline IR spectra.

This paper deals with experimental studies and with quantitative interpretation of the polarized IR spectra of hydrogen bonded glutaric acid crystals. The spectra were measured for the νO–H and νO–D band frequency regions at temperatures of 298 and 77 K, for the “beta” form of the glutaric acid crystal. The spectra were quantitatively reproduced with a sufficient accuracy on the basis of the “strong-coupling” model, when assuming the centrosymmetric dimer approximation for the crystalline spectral properties. The experimentally proved differences in the polarization properties between the long- and the short-wave branches of the νO–H and νO–D bands were interpreted as a result of the two simultaneously acting mechanisms: (i) promotion of the forbidden transition in the IR region for the totally symmetric protonic vibrations in the (COOH)2 and (COOD)2 cycles of the crystalline lattices, and (ii) the influence of the static “out-of-plane ” deformations of the hydrogen bonds in the cycles on the dimer selection rules. The same mechanisms are responsible for temperature effects in the spectra.

In this paper we discuss the problem of a stable coexistence of the X–H…Y and X–D…Y bonds in one cyclic dimer of the hydrogen bonds. Comparing the spectra of the partially deuterated dimeric systems with those of the pure hydrogen bonded systems, and considering the results of calculations of the dimeric IR spectra, based on the `strong-coupling' model, we found no convincing evidence for the existence of the nonsymmetrical dimers in mixtures of the hydrogen isotope derivative cyclic dimers, although such spectra should easily be distinguished from those of the symmetric dimers of the hydrogen bonds. This isotopic effect seems to apply to the different hydrogen bond cyclic dimeric systems and to be generally widespread in nature. We suggest that the mechanism, which restricts simultaneous existence of the two different hydrogen isotope hydrogen bonds in one dimer, is of a vibronic nature and results from the collective properties of hydrogen bonds. The nonsymmetrical, different hydrogen isotope dimers, most likely characterized by a higher energy, when compared with the symmetrical ones, are considerably rarer than predicted by a statistical approach. We roughly estimated the excess energy value for the mixed hydrogen isotope dimers as equal to 1.5–2.0 kcal mol−1 of the dimers.

In this paper a mechanism is analysed of a long-distance influence of the hydrogen atoms of C-H groups (peripherial with respect to the hydrogen bonds) on the spectral properties of the centrosymmetric dimers of hydrogen bonds, along with the so called ‘long-range’ isotopic effects measured in the frequency range of the ν X-H and ν X-D bands. For this purpose a model of the vibronic coupling for the dimeric system was proposed, within the Herzberg-Teller approximation describing a resonance between the proton stretching vibrations ν X-H and the C-H group stretching vibrations ν C-H , which occur via the electrons of the systems. We derived the purely electronic matrix Hamiltonian of the dimer, responsible for its spectral properties. The consequence of the model is enhancement of an uncommon spectral phenomenon depending on breaking of the vibrational selection rules for the dimer in the IR range, due to promotion of the symmetry forbidden excitation of the totally symmetric protonic vibrations. This effect was found to be mass-dependent on all the hydrogen atoms in the model system. From this model it also seen that the strongest ‘long-range’ isotopic effects correspond with the case when all the hydrogen isotopes in the dimer are identical.

Kanigowski, P., Flakus, A., Oset, M., Kowalewska, A., Rykaczewki, M., & Kukwa, M. 2016. The lichen family Parmeliaceae in Poland. Xanthoparmelia species containing usnic acid. — Herzogia 29: 108–119. In a study of the Xanthoparmelia species containing usnic acid in Poland, six taxa have been recognized. Xanthoparmelia plittii is new to Poland. Some of the material is referred to as X. aff. cumberlandia. Xanthoparmelia conspersa is the most common species of the group in Poland (c. 67% of all records). Xanthoparmelia angustiphylla is widespread, but less common (c. 20% of all records). The remaining Xanthoparmelia taxa in Poland, i.e. X. aff. cumberlandia, X. mougeotii, X. plittii and X. stenophylla, are rare or very rare in the country. The distribution and threat status of all taxa, their habitat requirements, morphology and secondary chemistry are discussed and notes on similar taxa are made.

Polarized IR spectra of hydrogen-bonded acetone oxime and 3,5-dimethylpyrazole crystals were measured at 293 and 77 K in the ν(X-H) and ν(X-D) band frequency ranges. These crystals contain molecular trimers in their lattices. The individual crystal spectral properties remain in a close relation with the electronic structure of the two different molecular systems. We show that a vibronic coupling mechanism involving the hydrogen-bond protons and the electrons on the π-electronic systems in the molecules determines the way in which the vibrational exciton coupling between the hydrogen bonds in the trimers occurs. A strong coupling in 3,5-dimethylpyrazole trimers prefers a "tail-to-head"-type Davydov coupling widespread via the π-electrons. A weak through-space exciton coupling in acetone oxime trimers involves three adjacent hydrogen bonds in each cycle. The relative contribution of each exciton coupling mechanism in the trimer spectra generation is temperature and the molecular electronic structure-dependent. This explains the observed difference in the temperature-induced evolution of the compared spectra. The mechanism of the H/D isotopic "self-organization" processes in the crystal hydrogen bonds was also analyzed. The two types of the hydrogen-bond trimers exhibit the same way, in which the H/D isotopic recognition mechanism occurs. In acetone oxime and 3,5-dimethylpyrazole trimers, identical hydrogen isotope atoms exist in these entire hydrogen-bond systems.

Polarized IR spectra of 3- and 4-methylacetanilide as well as their deuterium derivative crystals were measured at 293 K and at 77 K by a transmission method. The obtained results were interpreted within the limits of the “strong-coupling” theory. This approach facilitated the understanding of the H/D isotopic, temperature and dichroic effects observed in the hydrogen bond IR spectra. The existence of H/D isotopic “self-organization” phenomenon, depending on the non-random distribution of protons and deuterons in the crystal lattices of isotopically diluted samples of a compound was ascertained. This effect resulted from the dynamical co-operative interactions involving the closely spaced hydrogen bonds, each belonging to a different chain of associated 3- and 4-methylacetanilide molecules. In the case of 4-methylacetanilide crystals weaker but non-negligible exciton coupling also involved adjacent hydrogen bonds in each molecular chain and the H/D isotopic “self-organization” mechanism concerned at least four hydrogen bonds from each unit cell. The source of these phenomena was ascribed to the molecular electronic properties determined by aromatic rings linked to nitrogen atoms of the amide fragments.

This article focuses on the problem of remarkably strong changes in the fine structure patterns of the ν(N-H) and ν(N-D) bands attributed to the hydrogen and deuterium bonds accompanying the phase transition, which occurs between two polymorphic forms of oxindole. The lattices of these two different crystals contain hydrogen-bonded cyclic dimers differ in their geometry parameters. The source of these differences in the polymorph spectral properties results from the geometry relations concerning the dimers constituting the lattice structural units. In the case of the "alpha" phase, the hydrogen bond lengths of the dimers differ by 0.18 Å. This leads to the "off-resonance exciton coupling" weakly involving the dimer hydrogen bonds. For the "beta" phase, with practically symmetric dimers in the lattice, the spectra become typical for centrosymmetric hydrogen bond systems due to the full resonance of the proton or deuteron vibrations.

This article presents the investigation results of the polarized IR spectra of the hydrogen bond in N-phenylacrylamide crystals measured in the frequency range of the proton and deuteron, ν(N-H) and ν(N-D), stretching vibration bands. The basic spectral properties of the crystals were interpreted quantitatively in terms of the "strong-coupling" theory. The proposed model of the centrosymmetric dimer of hydrogen bonds facilitated the explanation of the well-developed, two-branch structure of the ν(N-H) and ν(N-D) bands as well as the isotopic dilution effects in the spectra. The vibronic mechanism of the generation of the long-wave branch of the ν(N-H) band ascribed to the excitation of the totally symmetric proton vibration was elucidated. The complex fine structure pattern of ν(N-H) and ν(N-D) bands in N-phenylacrylamide spectra in comparison with the spectra of other secondary amide crystals (e.g., N-methylacetamide and acetanilide) can be accounted for in terms of the vibronic model for the forbidden transition breaking in the dimers. On the basis of the linear dichroic and temperature effects in the polarized IR spectra of N-phenylacrylamide crystals, the H/D isotopic "self-organization" effects were revealed.