Oligourea molecular lifter triggered by electric field

Dziubak, Damian; Puszko, Anna K.; Bachurska, Paulina; Pulka-Ziach, Karolina; Sęk, Sławomir

doi:10.1016/j.electacta.2021.139634

Cited by 1 publication

(6 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Nevertheless, the urea I band is significantly shifted toward lower frequencies compared to the typical value reported for oligourea ∼1630–1640 cm –1 . The displacement of the urea I band in SEIRA spectra toward lower frequencies for surface-confined long oligourea has been reported in prior literature, a phenomenon attributed to the isotope exchange effect and possibly increased strength of hydrogen bonds . While this holds true in this investigation, the observed shift in our case is notably more pronounced, underscoring the unique and intensified impact of the increased hydrogen bonding strength in the current experimental system.…”

Section: Resultssupporting

confidence: 79%

“…While this holds true in this investigation, the observed shift in our case is notably more pronounced, underscoring the unique and intensified impact of the increased hydrogen bonding strength in the current experimental system. In the spectra of surface-confined long oligourea, there is also a weak band around 1650–1660 cm –1 . However, in our examined compound, this band is significantly more pronounced, particularly as a distinct negative feature at ∼1660 cm –1 .…”

Section: Resultsmentioning

confidence: 46%

“…In the spectra of surface-confined long oligourea, there is also a weak band around 1650−1660 cm −1 . 32 However, in our examined compound, this band is significantly more pronounced, particularly as a distinct negative feature at ∼1660 cm −1 . We believe that these findings strongly indicate that upon adsorption and under the influence of an electric field, there is a substantial amplification in the strength of hydrogen bonding within the oligourea backbone.…”

Section: ■ Results and Discussionmentioning

confidence: 51%

“…Moreover, certain side groups, like amine or carboxyl acid, can be introduced to the oligourea helix without disrupting its structure . In our previous studies, we have used oligourea foldamers as electron transfer mediators and have shown that the mechanism of that process was connected with the length of the oligomer, hence the thickness of the SAM. , Further, we have explored the stimuli–responsive properties of oligourea thin films immobilized on gold. , We have found that the potential-dependent changes in the orientation of oligourea molecules resulted from the presence (and the direction) of the significant dipole moment of oligourea helices and, for electroactive oligoureas with a ferrocene moiety, also by the presence of a positive charge of the redox site generated upon oxidation.…”

Section: Introductionmentioning

confidence: 99%

“…29,30 Further, we have explored the stimuli−responsive properties of oligourea thin films immobilized on gold. 31,32 We have found that the potential-dependent changes in the orientation of oligourea molecules resulted from the presence (and the direction) of the significant dipole moment of oligourea helices and, for electroactive oligoureas with a ferrocene moiety, also by the presence of a positive charge of the redox site generated upon oxidation.…”

Section: ■ Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Stimuli-Responsive Oligourea Molecular Films

Grempka,

Dziubak,

Puszko

et al. 2024

ACS Appl. Mater. Interfaces

Self Cite

View full text Add to dashboard Cite

We have designed and synthesized a helical cysteamineterminated oligourea foldamer composed of ten urea residues featuring side carboxyl and amine groups. The carboxyl group is located in proximity to the C-terminus of the oligourea and hence at the negative pole of the helix dipole. The amine group is located close to the N-terminus and hence at the positive pole of the helix dipole. Beyond the already remarkable dipole moment inherent in oligourea 2.5 helices, the incorporation of additional charges originating from the carboxylic and amine groups is supposed to impact the overall charge distribution along the molecule. These molecules were self-assembled into monolayers on a gold substrate, allowing us to investigate the influence of an electric field on these polar helices. By applying surface-enhanced infrared reflection−absorption spectroscopy, we proved that molecules within the monolayers tend to reorient themselves more vertically when a negative bias is applied to the surface. It was also found that surface-confined oligourea molecules affected by the external electric field tend to rearrange the electron density at urea groups, leading to the stabilization of the resonance structure with charge transfer character. The presence of the external electric field also affected the nanomechanical properties of the oligourea films, suggesting that molecules also tend to reorient in the ambient environment without an electrolyte solution. Under the same conditions, the helical oligourea displayed a robust piezoresponse, particularly noteworthy given the slender thickness of the monolayer, which measured approximately 1.2 nm. This observation demonstrates that thin molecular films composed of oligoureas may exhibit stimulus−responsive properties. This, in turn, may be used in nanotechnology systems as actuators or functional films, enabling precise control of their thickness in the range of even fractions of nanometers.

show abstract

Section: Resultssupporting

confidence: 79%

Section: Resultsmentioning

confidence: 46%

Section: ■ Results and Discussionmentioning

confidence: 51%