Structuring of Amide Cross‐Linked Non‐Bridged and Bridged Alkyl‐Based Silsesquioxanes

Nunes, S. C.; Bermúdez, V. de Zea

doi:10.1002/tcr.201700096

Cited by 6 publications

(2 citation statements)

References 62 publications

(111 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This concept was proposed by Ke et al to produce superhydrophobic coatings on glass . The chemical simplicity of epicuticular wax (essentially 1-octacosanol) is particularly attractive for the synthesis of silsequioxane materials, a concept that has been extensively explored by some of us. − …”

Section: Discussionmentioning

confidence: 99%

The Surfaces of the Ceratonia siliqua L. (Carob) Leaflet: Insights from Physics and Chemistry

et al. 2021

View full text Add to dashboard Cite

The production of superhydrophobic coatings inspired by the surface of plant leaves is a challenging goal. Such coatings hold a bright technological future in niche markets of the aeronautical, space, naval, building, automobile, and biomedical sectors. This work is focused on the adaxial (top) and abaxial (bottom) surfaces of the leaflet of the Ceratonia silique L. (carob), a high-commercial-value Mediterranean tree cultivated in many regions of the world. The adaxial and abaxial surfaces feature hydrophobic and superhydrophobic behaviors, respectively. Their chemical composition is very simple: monopalmitin ester and palmitic acid are protuberant in the epicuticular and intracuticular wax layers of the adaxial surface, respectively, whereas 1-octacosanol dominates in the abaxial wax layers. In both surfaces, epicuticular wax is organized along a randomly oriented and intricate network of nanometer-thick and micrometer-long plates, whose density and degree of interconnection are significantly higher in the abaxial surface. The measured tilting angles for the abaxial surface (12–70°) reveal unusual variable density and water adhesion of the nanostructured plate-based texture. Optical measurements demonstrate that light reflectance/absorbance of the glaucous abaxial surface is significantly higher/lower than that of the nonglaucous adaxial surface. In both surfaces, diffuse reflectance is dominant, and the absorbance is weakly dependent on the light incidence angle. We show that the highly dense nanostructured platelike texture of the epicuticular abaxial layer of the C. siliqua leaflet works as a sophisticated light and water management system: it reflects solar radiation diffusely to lower the surface temperature, and it has superhydrophobic character to keep the surface dry. Such attributes enable efficient gas exchange (photosynthesis and respiration), transpiration, and evaporation. To mimic for the first time the abaxial surface, a templation approach was adopted using poly(dimethylsiloxane) (PDMS)/poly(methylphenylsiloxane) (PMPS) positive/negative replicas and a soft polymer/siloxane negative replica produced by the sol–gel process. Because high topographical variations of the biotemplate and wax adhesion to the biohybrid film affected the replication quality, the reproduction of the wax texture via the synthesis of 1-octacosanol-grafted siloxane-based hybrid materials is proposed as a suitable route to duplicate the abaxial surface with high fidelity. The natural chemical/physical strategy adopted by the C. siliqua leaflet to face the harsh Mediterranean climate is a powerful source of bioinspiration for the development of diffuse reflecting and superhydrophobic material systems with foreseen applications as dual-functional antiglare and water-repelling coatings.

show abstract

Section: Discussionmentioning

confidence: 99%

The Surfaces of the Ceratonia siliqua L. (Carob) Leaflet: Insights from Physics and Chemistry

et al. 2021

View full text Add to dashboard Cite

show abstract

“…Despite the information abundance on the amide functionality, there is a continued interest in chemical synthesis, biosynthesis and reactivity of amides due to their importance in medicine, biology, chemistry and other related interdisciplinary sciences . This relevance encourages the research of the amide group's fundamental characteristics, e. g. the cis ‐ trans isomerization barrier, the resonance energy or acid‐base properties.…”

Section: Introductionmentioning

confidence: 99%

How Strong is Hydrogen Bonding to Amide Nitrogen?

et al. 2020

View full text Add to dashboard Cite

The protonation of the carboxamide nitrogen atom is an essential part of in vivo and in vitro processes (cis‐trans isomerization, amides hydrolysis etc). This phenomenon is well studied in geometrically strongly distorted amides, although there is little data concerning the protonation of undistorted amides. In the latter case, the participation of amide nitrogen in hydrogen bonding (which can be regarded as the incipient state of a proton transfer process) is less well‐studied. Thus, it would be a worthy goal to investigate the enthalpy of this interaction. We prepared and investigated a set of peri‐substituted naphthalenes containing the protonated dimethylamino group next to the amide nitrogen atom (“amide proton sponges”), which could serve as models for the study of an intramolecular hydrogen bond with the amide nitrogen atom. X‐Ray analysis, NMR spectra, basicity values as well as quantum chemical calculations revealed the existence of a hydrogen bond with the amide nitrogen, that should be attributed to the borderline between moderate and weak intramolecular hydrogen bonds (2–7 kcal ⋅ mol−1).

show abstract

Direct Determination of POSS Cage Structure in a Self‐Assembled Ionic Bridged Silsesquioxane by Using the Total Pair Distribution Function G(r) and Density Functional Theory

Schneid,

de Lima,

Ferreira

et al. 2024

Chemistry An Asian Journal

View full text Add to dashboard Cite

In the present study, both short‐range and long‐range structural features of an ionic bridged silsesquioxane, specifically one containing the 1,4‐diazoniabicyclo[2.2.2]octane chloride group (ISSQ), were elucidated. This ionic silsesquioxane was synthesized via direct polycondensation of a bridged organosilane precursor, without any additional functionalization step. Si‐O‐Si cage structures typical of Polyhedral Oligomeric Silsesquioxanes (POSS) were identified. The average interatomic distances of the POSS cages, including the open T8 cage and the T12 cage for the ISSQ, as well as the T8 cage for a commercially available pendant POSS were determined. It is the first report of the interatomic distance determination of POSS cage; achieved by using total pair distribution function G(r) values obtained through high‐resolution synchrotron X‐ray diffraction combined with density functional theory (DFT) calculations. The application of DFT was crucial for accurately assigning X‐ray peaks and verifying structural details. Furthermore, the analysis of X‐ray diffraction peaks and the examination of crystalline domains via transmission electron microscopy enabled the proposal of a hexagonal arrangement of Si–O–Si cages over long ranges within the ionic bridged silsesquioxane. This proposed arrangement highlights a distinctive structural organization that could impact the material's properties and applications.

show abstract

Structuring of Amide Cross‐Linked Non‐Bridged and Bridged Alkyl‐Based Silsesquioxanes

Cited by 6 publications

References 62 publications

The Surfaces of the Ceratonia siliqua L. (Carob) Leaflet: Insights from Physics and Chemistry

The Surfaces of the Ceratonia siliqua L. (Carob) Leaflet: Insights from Physics and Chemistry

How Strong is Hydrogen Bonding to Amide Nitrogen?

Direct Determination of POSS Cage Structure in a Self‐Assembled Ionic Bridged Silsesquioxane by Using the Total Pair Distribution Function G(r) and Density Functional Theory

Contact Info

Product

Resources

About