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Self-assembled Peptide Nanostructures and Their Applications
Published in Klaus D. Sattler, st Century Nanoscience – A Handbook, 2020
The solvent is one of the important parameters in the self-assembly process as it affects supramolecular assembly by forming solvent-bridged H-bonding network. The molecular assembly may be changed upon changing the solvent composition. Solvents with different polarity and H-bonding ability may influence the self-assembly process. The FF dipeptide undergoes self-assembly in polar solvents to form flower-like microcrystal. The dipeptide also forms long nanofibers in nonpolar solvents like toluene. The reason behind this anomaly is that the nonpolar solvent (toluene) breaks the relationship between hydrophobic and hydrogen bonding interactions and induces the aromatic π–π stacking interactions, which then determine the self-assembly pathway (Zhu et al. 2010). Another recent study revealed that trace amounts of polar solvents in DCM played a key role in nanofibril formation (Wang et al. 2016a). A perylene bisimide-(di)glycine-tyrosine based (PBI-[GY]2) bolaamphiphile formed nanofibers in water. However, in the presence of trace amounts of THF in water followed by solvent evaporation, the bolaamphiphile formed a nanosphere structure (Figure 2.8). A trace amount of THF as a proton acceptor solvent may change the H-bonding network, leading to tuning of the morphology from nanofibers to spherical assembly (Bai et al. 2014, Wang et al. 2017).
Recent Developments toward the Synthesis of Supramolecular Bioelectronicc Nanostructures
Published in Šeila Selimovic, Nanopatterning and Nanoscale Devices for Biological Applications, 2017
John D. Tovar, Stephen R. Diegelmann, Brian D. Wall
Supramolecular assembly is a powerful approach to construct a variety of low-dimensional objects with a variety of unique functions. Conducting polymers are also powerful biomaterials for nerve repair and cardiac regulation. Exciting new developments in the supramolecular assembly of well-defined π-conjugated electronic materials in physiological environments is now underway. It will soon be possible to construct 1-D nanomaterials that can directly interface useful electrical function with living cells, be it for therapeutic or diagnostic applications. The ability to influence cells through external nanostructured biomaterials as well as the ability to detect cellular events or harness biological energy sources will provide many new and exciting scientific inquiries in the coming years, and self-assembled organic electronic materials stand to play large roles in these important pursuits.
Picometer Detection by Adaptive Holographic Interferometry
Published in Klaus D. Sattler, Fundamentals of PICOSCIENCE, 2013
As the literature has over 700 papers on self-assembled monolayers measured by STM, the author highlights only one interesting example here. Cai and Bernasek studied the adsorption of octadecanol on HOPG. 72 Although this molecule is achiral, they found that the alkane chain undergoes distortion as it adsorbs onto the graphite surface, leading to the observed asymmetry in the resultant arrangement of the molecules on the surface (Figure 8.12). The system involves supramolecular assembly by hydrogen bonding. The adsorbate conformation on the surface is different from that of the molecule in solution. The asymmetric bending of the molecule due to the interaction with the substrate breaks the achiral symmetry of the substrate.
The strange case of metal coordination in disubstituted-biquinolines: competition between ligands and formation of a hybrid organic/inorganic Cu(II)/Cu(I) ternary cocrystal
Published in Journal of Coordination Chemistry, 2022
Francesca Scarpelli, Massimo La Deda, Nicolas Godbert, Nadia Marino, Alessandra Crispini, Iolinda Aiello
Despite the different geometry of the two copper complexes, the stability of the supramolecular assembly in the ternary cocrystal is ensured by the extremely favored intermolecular interactions that the biq-OH molecule brings, hydrogen bonding, C-H—π and π-π aromatic interactions. On the basis of the crystal structure determination of both biq-OH ligand and {[Cu(Trop)2][Cu(biq-OH)2]Cl}(biq-OH)·H2O cocrystal, the principal intermolecular interactions between molecules in their crystalline environment have been derived from analysis of the crystal packing. Moreover, the HS analysis and the 2 D fingerprint plots performed on both crystals highlighted that van der Waal forces exert an important role on stabilization of both crystal structures. In particular, the calculation of the ER for interacting chemical elements, obtained comparing the contacts found in the crystal with those computed from the HS analysis, has revealed the propensity of biq-OH to establish extensive π-π stacking interactions between both pyr and phen rings, as well as -CH2O-H—O and C-H—OHCH2- hydrogen bonding interactions, despite its crystalline environment. The latter contacts are highly favored and could be considered the driving force for the presence of [Cu(Trop)2] as a component within the ternary cocrystal, considering formation of hydrogen bonds with the acceptor oxygen atoms of the coordinated tropolonate ligands.
Modes of interaction and thermodynamic behavior of aggregation of CTAB + BSA mixtures in diols media: effects of diols composition and temperature
Published in Chemical Engineering Communications, 2023
Md. Anamul Hoque, Shamim Mahbub, Md. Tuhinur R. Joy, Malik Abdul Rub, Shahed Rana, Dileep Kumar, Yousef G. Alghamdi, Abdullah M. Asiri, Mohammed Abdullah Khan
Nielsen et al. (2000) obtained negative values of free energy, negative enthalpy, and positive entropy changes of SDS micelle formation in the presence of BSA using the technique of isothermal titration calorimetry. The authors suggested that hydrophobic interactions are the predominant forces for the micelle formation. Kumari et al. (2018) described the binding of an IL-type gemini surfactant to BSA as a spontaneous and exothermic process. They reported that the process is entropy focused and that the principal binding forces are hydrophobic interactions. Chakraborty et al. (2009) reported the existence of interactions amongst BSA and alkyl trimethylammonium bromides, which increased with the alkyl chain length, signifying the presence of hydrophobic interactions. The existence of cationic binding sites close to the hydrophobic areas of BSA indicates that electrostatic and hydrophobic interactions function together supportively (Chakraborty et al. 2009). Sharma et al. (2020) acquired negative ΔH0m and positive ΔS0m values for the mixture of CPC and BSA in aqueous glycerol and aqueous DMSO mixed media; they discussed the opportunity for the presence of van der Waals forces and hydrogen bonding, which might promote micelle development and a supramolecular assembly. Banipal et al. (2016) investigated the binding of nicotinic acid (NA) with BSA through isothermal titration calorimetry (ITC), light scattering, spectroscopic and density functional theory techniques. From ITC study, the authors acquired negative ΔH0m values, which experience an enrichment through rise of temperature, and they suggested the strong electrostatic and hydrophobic interactions between NA and BSA in the case of first binding site of BSA. Also, they explained the existence of pi-pi interactions amongst NA and BSA.
Design and molecular docking studies of {N1-[2-(amino)ethyl]ethane-1,2-diamine}-[tris(oxido)]-molybdenum(VI) complex as a potential antivirus drug: from synthesis to structure
Published in Journal of Coordination Chemistry, 2023
Hirshfeld surface analysis was performed to give insight into the packing and intermolecular interactions [31]. The Hirshfeld surface is a graphical visualization tool used to analyze the nature of the intermolecular interactions within the crystal structure. By evaluating the electron density in the surrounding environment of the molecule, the supramolecular assembly can be analyzed. The molecular Hirshfeld surfaces (HSs) and their associated two-dimensional fingerprint plots (FPs) were generated for 1, based on their crystallographic information file (cif), using Crystal Explorer 17.5 software [32]. The HS provides qualitative information about all intermolecular interactions, whereas FPs produces the most efficient interactive graphics to obtain intermolecular interaction quantitatively. The 3D graphical plots of the HSs are mapped over the dnorm (normalized contact distance) surface which enables us to visualize the various intermolecular interactions in the crystal lattice and allows us to gain insight into the crystal packing behavior. The HS is reduced to 2D fingerprint plots by obtaining standard resolution of molecular HS on calculating the di and de for each surface point. The di and de are the distance to the Hirshfeld surface from the nearest internal nucleus (inside the Hirshfeld surface) and external nucleus (outside the Hirshfeld surface), respectively. Further, the data are binned into a discrete interval of di and de to generate a 2D histogram with a scale of 0.2 Å. The 2D FPs give a summary of the frequency of each combination di and de across the surface of a molecule and indicate the interactions present as well as the relative area of the surface corresponding to those interactions [33–35].