An infrared study of various dialkylureas in solution

Mido, Yoshiyuki

doi:10.1016/0584-8539(73)80025-x

Cited by 51 publications

(28 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…At R urea > 0.26 only one component occurring at 1677 cm −1 was evident. Considering the CO vibrational frequency of monomeric urea (1734 cm −1 ) and urea dissolved in acetonitrile (1695 cm −1 ) (29) and considering that H-bonding association leads to a decrease in the CO vibrational frequency (36), this behavior is consistent with the hypothesis that urea is predominantly dispersed as monomers within the AOT micellar cores at R urea = 0.13, whereas at higher R urea values it forms molecular clusters. Besides, the observed trend of the relative intensities of the urea CO stretching components with R urea suggests that with increasing R urea , a rapidly increasing fraction of the urea CO groups are engaged in perturbed hydrogen bonds with the NH 2 groups.…”

Section: Aot and Urea Co Stretching Bandssupporting

confidence: 80%

FT-IR Investigation of the Urea State in AOT Reversed Micelles

Calvaruso

Minore

Liveri

2001

Journal of Colloid and Interface Science

View full text Add to dashboard Cite

Section: Aot and Urea Co Stretching Bandssupporting

confidence: 80%

FT-IR Investigation of the Urea State in AOT Reversed Micelles

Calvaruso

Minore

Liveri

2001

Journal of Colloid and Interface Science

View full text Add to dashboard Cite

“…Relative to those of non-hydrogen-bonding urea groups, the amide I and II bands of all the OPV-ureas are shifted to shorter and longer wavenumbers, respectively. [33] These shifts are typical of urea groups engaged in hydrogen-bonded interactions. The largest shift in the amide I band of 1 a might indicate the presence of the strongest hydrogen-bonding interactions among the three compounds.…”

mentioning

confidence: 96%

“…[33] The positions of amide I and II bands differ slightly between the compounds, and appear at 1631 and 1559 cm À1 for 1 a, 1636 and 1557 cm À1 for 1 b, and 1644 and 1559 cm À1 for 2. Relative to those of non-hydrogen-bonding urea groups, the amide I and II bands of all the OPV-ureas are shifted to shorter and longer wavenumbers, respectively.…”

mentioning

confidence: 98%

Supramolecular Polymerization and Polymorphs of Oligo(p‐phenylene vinylene)‐Functionalized Bis‐ and Monoureas

Yagai

Kubota

Iwashima

et al. 2008

Chemistry A European J

View full text Add to dashboard Cite

Bis- and monoureas hybridized with the oligo(p-phenylene vinylene) (OPV) pi-electronic segment and 3,4,5-tridodecyloxyphenyl wedge were synthesized and their supramolecular polymerization in diluted solution, gel formation in concentrated solution, and liquid crystallinity in bulk state were investigated. Bisurea 1a featuring a hexamethylene linker showed the highest supramolecular polymerization ability and formed tapelike nanofibers that can gelate various organic solvents. On the other hand, bisurea 1b featuring a dodecamethylene linker and monourea 2 showed a lower degree of supramolecular polymerization, resulting in gel formations in a smaller variety of solvents. These results clearly reflect a high level of cooperativity between the two urea sites and the two OPV segments of 1a upon hydrogen-bonding and pi-pi stacking interactions, respectively. When the gels of 1a, 1b, and 2 were dried, all the compounds self-organized into multilamellar superstructures. Thermal treatment of these lamellae at high temperatures induces columnar liquid-crystalline mesophases as a result of microsegregation between the rigid OPV parts and the molten aliphatic wedges. These results demonstrate that the present molecular constituent is very useful for fabricating dye-based functional assemblies providing nanoscale pi-electronic fibers, and solvent-incorporated and bulk soft materials.

show abstract

“…These spectral changes indicate that gel formation is accompanied by the formation of hydrogen bonds between the urea groups. [18] As shown in Table 1, compound 1 did not gelate any of the solvents investigated. However, we were able to isolate crystals from 1-octanol, suitable for X-ray analysis (Figure 2).…”

Section: Resultsmentioning

confidence: 92%