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Rodríguez S, Rocha J, Fernandes M, Ravishankar AP, Steinbrück N, Cruz R, Bacelar E, Kickelbick G, Anand S, Crespí AL, Casal S, de Zea Bermudez V. The Surfaces of the Ceratonia siliqua L. (Carob) Leaflet: Insights from Physics and Chemistry. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:2011-2028. [PMID: 33533623 DOI: 10.1021/acs.langmuir.0c02806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
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.
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Affiliation(s)
- S Rodríguez
- CQ-VR, University of Trás-os-Montes e Alto Douro, 5000-811 Vila Real, Portugal
| | - J Rocha
- CQ-VR, University of Trás-os-Montes e Alto Douro, 5000-811 Vila Real, Portugal
- Herbarium and Botanical Garden, University of Trás-os-Montes e Alto Douro, 5000-811 Vila Real, Portugal
| | - M Fernandes
- CQ-VR, University of Trás-os-Montes e Alto Douro, 5000-811 Vila Real, Portugal
- Department of Chemistry, University of Trás-os-Montes e Alto Douro, 5000-811 Vila Real, Portugal
| | - A P Ravishankar
- Department of Applied Physics, School of Engineering Sciences, KTH Royal Institute of Technology, Albanova University Centre, Roslagstullsbacken 21, SE-106 91 Stockholm, Sweden
| | - N Steinbrück
- Inorganic Solid State Chemistry, Saarland University, Campus Building C4 1, 66123 Saarbrücken, Germany
| | - R Cruz
- LAQV-REQUIMTE, Department of Chemical Sciences, Faculty of Pharmacy, Laboratory of Bromatology and Hydrology, University of Porto, 4050-313 Porto, Portugal
| | - E Bacelar
- CITAB, Department of Biological and Environmental Engineering, University of Trás-os-Montes e Alto Douro, 5000-811 Vila Real, Portugal
| | - G Kickelbick
- Inorganic Solid State Chemistry, Saarland University, Campus Building C4 1, 66123 Saarbrücken, Germany
| | - S Anand
- Department of Applied Physics, School of Engineering Sciences, KTH Royal Institute of Technology, Albanova University Centre, Roslagstullsbacken 21, SE-106 91 Stockholm, Sweden
| | - A L Crespí
- Herbarium and Botanical Garden, University of Trás-os-Montes e Alto Douro, 5000-811 Vila Real, Portugal
- CITAB, Department of Biological and Environmental Engineering, University of Trás-os-Montes e Alto Douro, 5000-811 Vila Real, Portugal
| | - S Casal
- LAQV-REQUIMTE, Department of Chemical Sciences, Faculty of Pharmacy, Laboratory of Bromatology and Hydrology, University of Porto, 4050-313 Porto, Portugal
| | - V de Zea Bermudez
- CQ-VR, University of Trás-os-Montes e Alto Douro, 5000-811 Vila Real, Portugal
- Department of Chemistry, University of Trás-os-Montes e Alto Douro, 5000-811 Vila Real, Portugal
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Mikshiev VY, Pozharskii AF, Filarowski A, Novikov AS, Antonov AS, Tolstoy PM, Vovk MA, Khoroshilova OV. How Strong is Hydrogen Bonding to Amide Nitrogen? Chemphyschem 2020; 21:651-658. [PMID: 31953976 DOI: 10.1002/cphc.201901104] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 12/18/2019] [Indexed: 12/23/2022]
Abstract
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 ).
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Affiliation(s)
- Vladimir Y Mikshiev
- Institute of Chemistry, St. Petersburg State University, Universitetskii pr. 26, 198504, St. Petersburg, Russian Federation
| | - Alexander F Pozharskii
- Department of Organic Chemistry, Southern Federal University, Zorge str. 7, 344090, Rostov-on-Don, Russian Federation
| | - Alexander Filarowski
- Faculty of Chemistry, Wroclaw University, F. Joliot-Curie str. 14, 50-383, Wroclaw, Poland
- Industrial University of Tyumen, Volodarskogo str. 38, 625000, Tyumen, Russian Federation
| | - Alexander S Novikov
- Institute of Chemistry, St. Petersburg State University, Universitetskii pr. 26, 198504, St. Petersburg, Russian Federation
| | - Alexander S Antonov
- Institute of Chemistry, St. Petersburg State University, Universitetskii pr. 26, 198504, St. Petersburg, Russian Federation
| | - Peter M Tolstoy
- Institute of Chemistry, St. Petersburg State University, Universitetskii pr. 26, 198504, St. Petersburg, Russian Federation
| | - Mikhail A Vovk
- Institute of Chemistry, St. Petersburg State University, Universitetskii pr. 26, 198504, St. Petersburg, Russian Federation
| | - Olesya V Khoroshilova
- Institute of Chemistry, St. Petersburg State University, Universitetskii pr. 26, 198504, St. Petersburg, Russian Federation
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