Intramolecular and intermolecular hydrogen bonds in aminophenols

Abstract

539.1.047;543.42 IR-Fourier spectroscopy methods are adopted to study intramolecular and intermolecular hydrogen bonds that form in CCl 4 solutions of aminophenol derivatives and in a solid phase of these compounds pressed in KBr. If a hydroxyl group is present in the molecule in the ortho-position to an amino group, then intramolecular interactions between OH and NH groups will take place in aminophenol solutions. Intramolecular O-H⋅⋅⋅O=S=O and N-H⋅⋅⋅O=S=O hydrogen bonds are found in solutions of compounds containing a sulfonamide fragment. Additional acylation of the amino group causes an intramolecular O-H⋅⋅⋅O=C hydrogen bond to form in solutions. Functional groups OH, NH, SO 2 , and C=O interact with one another in various ways in the solid phase to form intermolecular hydrogen bonds in aminophenols.Keywords: aminophenol, IR spectrum, intramolecular hydrogen bond, intermolecular hydrogen bond.Introduction. Derivatives of phenols and aromatic amines are effective antioxidants and, therefore, are used widely as stabilizers of industrial organic materials and food preservatives [1,2]. Certain derivatives of diphenols [3,4] and aminophenols (AP) [5, 6] turned out to be effective regulators of radiation-induced reactions involving various types of organic radicals. It was found that the antioxidant properties of AP derivatives are diminished upon forming intramolecular hydrogen bonds (IHB) in solution and are enhanced when the hydroxyls in the molecules occur in the free state [7]. Antioxidants can be used effectively as chemotherapy agents in the battle against viral pathologies [8]. Experiments with cell cultures showed that several derivatives of 2-amino-4,6-di-tert-butylphenol suppressed actively multiplication of Herpes simplex and flu A viruses [9][10][11][12][13][14] in addition to HIV [15]. Thus, a comprehensive study of these compounds, which have a broad array of functional properties, seems interesting for chemistry, pharmacology, and medicine.Herein we use IR-Fourier spectroscopy to investigate intramolecular and intermolecular interactions (IaMI and IrMI, respectively) of six structurally similar AP derivatives: 4-hydroxydiphenylamine (AP I), 2-hydroxydiphenylamine (AP II), 4,6-di-tert-butyl-2-morpholinophenol (AP III), 4,6-di-tert-butyl-2-(N,N-dimethyl)aminophenol (AP IV), N-(2-hydroxy-3,5-di-tert-butylphenyl)-4-methylbenzenesulfonamide (AP V), and N-(3,5-di-tert-butyl-2-hydroxyphenyl)acetamide (AP VI):

Hydrogen-Bonding-Facilitated Layer-by-Layer Growth of Ultrathin Organic Semiconducting Films

“…Grazing incidence small-angle X-ray scattering (GI-SAXS) also revealed clearly the multilayered structure (see Figure S3 in the Supporting Information). The FT-IR spectra of the crystals exhibited a strong OH stretching band near 3320 cm –1 , indicating that most hydroxyl groups in the crystals had formed hydrogen bonds . The observed layer periodicity was smaller than the length (3.16 nm) of a stretched bHP6T molecule, suggesting a tilt at the junction between the aromatic backbone and the hydroxypropyl groups, as illustrated in Figure d and similar to that reported previously for dialkyl 6T. , …”

“…The FT-IR spectra of the crystals exhibited a strong OH stretching band near 3320 cm −1 , indicating that most hydroxyl groups in the crystals had formed hydrogen bonds. 21 The observed layer periodicity was smaller than the length (3.16 nm) of a stretched bHP6T molecule, suggesting a tilt at the junction between the aromatic backbone and the hydroxypropyl groups, as illustrated in Figure 2d and similar to that reported previously for dialkyl 6T. 22,23 The AFM images of the 50 nm thick films shown in Figure 2 exhibited relatively low surface roughness values.…”

Arginine‐Substituted Phthalocyanine with Concentration‐Driven Self‐Disaggregation Performance: Synthesis, Properties and Mechanistic Study

“…It is well known that a hydrogen bond is closely related to molecular properties such as melting point, solubility, and spatial structure . Moreover, the above effects will vary with the type of hydrogen bond . For example, the formation of a hydrogen bond will change spatial structure of a molecule, and the steric hindrance of an intermolecular hydrogen bond is larger than for an intramolecular hydrogen bond in the same molecule.…”