Formation Of Supramolecules Research Articles

Self-organizing donor-acceptor assemblies of cobalt(II) porphyrin ligated with gold(III) porphyrin or fullero[60]pyrrolidine in liquid medium

This work provides the results of the spectroscopic, electrochemical, and photoelectrochemical study of the self-assembly in the systems consisting of (2,3,7,8,12,13,17,18-octaethylporphinato)cobalt(II) (CoOEP), (2,3,7,8,12,18-hexamethyl,13,17-diethyl,5-(4-pyridyl)porphinato)gold(III) chloride (ClAuP)/1′-N-methyl-2′-(pyridin-4-yl)pyrrolidino[3′,4′:1,2][60]fullerene (PyC60), and 1,2-dichlorobenzene/toluene as an electron donor, an acceptor, and a liquid medium, respectively. The results indicate axial coordination of electron acceptor functionalized by the pyridine units by cobalt(II) porphyrin with the donor-acceptor (ClAuP)2CoOEP/(PyC60)2CoOEP triad formation. The thermodynamic stability constant is (4.91 ± 1.10)×109 L2 mol−2 and (4.10 ± 1.14) ×1010 L2 mol−2 for ClAuP and PyC60, respectively. The formation of supramolecules was confirmed by UV, visible, IR, 1H NMR spectroscopy and cyclic voltammetry. DFT calculations (B3LYP+def2-SVP) detect octahedral geometry of the coordination center with the trans configuration of the axial ligands in the triads as well as the excited state calculations establish photoinduced electron transfer (PET). The jphavg value 266 μA cm−2 for the Ti|(ClAuP)2CoOEP|0.5 M Na2SO4|Pt system being 2–2.5 times higher compared with the precursors and slightly higher compared with (PyC60)2CoOEP shows that gold(III) porphyrin as an electron acceptor can be successfully used. The development of donor/acceptor platform selection strategy for the obtaining of photoactive supramolecules is an urgent task for future deriving of photovoltaic devices.

Mesomorphic and Dielectric Properties of Supramolecular 3,5-Diamino-1-dodecyl-1,2,4-triazole

The formation of a thermotropic smectic phase in 3,5-diamino-1-dodecyl-1,2,4-triazole was revealed by polarizing microscopy and DSC. Depending on heating and cooling conditions, transitions between different types of layered packings occur, which was evidenced by dielectric measurements. Quantum-chemical simulation established that the mesomorphism of 1,2,4-triazole derivatives is associated with the formation of supramolecules with a higher polarizability anisotropy. The calculation results confirmed the possibility of lateral hydrogen bonding which favors layered smectic packing.

Thermodynamics of the equilibrium of the reaction between (5,10,15,20-tetra(2-methoxyphenyl)porphinato)chloroindium(III) and pyridine

The results from thermodynamic and quantum-chemical studies of the reversible reaction between (5,10,15,20-tetra(2-methoxyphenyl)porphinato)chloroindium(III) and pyridine are reported. The main physicochemical parameters of properties of its supramolecular products are obtained and analyzed. The addition of pyridine molecules to metalloporphyrin proceeds in one step to attain an equilibrium state with the formation of supramolecules with a stoichiometry of 2: 1; spectral characteristics and parameters of the stability of the latter are identified. The possibility of using substituted indium(III)porphyrin for further research in the field of hybrid solar cells is discussed.

A review on protein oligomerization process

Enzymes or proteins are commonly present in oligomeric forms for active biological functions. The formation of protein oligomers, either in nature or by artificial means, can take place via covalent bonding or through weak-bond-network associations. Disulfide bonds are more common in forming covalent protein oligomers. Covalent bound protein oligomers usually have additional elements introduced, while proteins associated through weak-bond-networks usually do not involve any additional bound chemical groups. Proteins are commonly present in stable forms or folds. Oligomerization can occur when stable proteins unfold, creating exposed interfaces for association interactions. One well-known process of weak-bond-network oligomerization is domain swapping (DS). Separating the two touching/interacting domains creates opportunities for similar interactions with different protein molecules, leading to oligomerization. Both disulfide bonding and DS oligomerization can be dynamic (or reversible) at least at low Degree of Polymerizations (DPs). The dynamic nature of the protein oligomerization is important for bioactivity control. The morpheein model and the polymorph model are thus important in quantifying enzyme catalyzed biotransformations. Disulfide bonding and DS can act together to form supramolecules. The formation of supramolecules, such as amyloids, in nature can be benign or harmful. Industrial applications of protein oligomerization exploit the special functions /properties of the resultant supramolecules, such as multiple biofunctions, niche structure, etc..

ChemInform Abstract: Porphyrin‐Based Nanostructures for Sensing Applications

AbstractReview: 40 refs.

An iSAFT Density Functional Theory for Associating Polyatomic Molecules

The inhomogeneous statistical associating fluid theory (iSAFT) is extended to associating polyatomic molecular systems, using the inhomogeneous form of the association functional. The approach provides an accurate method for modeling a wide range of complex associating polyatomic systems, capable of investigating the full range of association for any bonding scheme. Theoretical results demonstrate the ability of the theory to model problems near surfaces and in the bulk over a wide range of conditions. The examples chosen in this paper elucidate the importance of such a theory, highlighting how reversible bonding governs the structure of a fluid near a surface and in confined environments, the molecular connectivity (formation of supramolecules, star polymers, etc.), and the phase behavior of the system (including reentrant order-disorder phase transitions).

Imidazolium Cations in Organic Chemistry: From Chemzymes to Supramolecular Building Blocs

The interest of imidazolium cations has grown enormously in the last few years especially in the field of green solvents and ionic liquids. Much attention has been focused on their physico-chemical properties and two properties can be highlighted: (i) the formation of carbenic species; and (ii) the formation of supramolecules via electrostatic, H-bonding and/or aromatic stacking interactions. The last property can be used to modify the molecular reactivity by the formation of supramolecular complexes between guests (reactive species) and the cationic receptors (imidazolium groups). The aim of this review is to bring together the areas of supramolecular assembly and imidazolium cations. Both imidazole and imidazolium cations are reviewed but only in their relation to achieving supramolecular organization.

Extraction and separation of a lysine-rich protein by formation of supramolecule between crown ether and protein in aqueous two-phase system

The macrocyclic calixarenes and crown ethers have recently been found to form hydrophobic complexes with the cationic protein cytochrome c (Cyt- c), by recognizing lysine residues on the protein surface. In the present study, it was found that the distribution of cytochrome c in Li 2SO 4/PEG aqueous two-phase system (ATPS) can be controlled by complexation with the crown ether dicyclohexano-18-crown-6 (DCH18C6). The protein was quantitatively extracted into the PEG-rich phase in the presence of DCH18C6 and perchlorate ion. Of various crown ethers and their analogues that were investigated, only DCH18C6 was able to extract cytochrome c into the PEG-rich phase. Extraction of cytochrome c in the ATPS using DCH18C6 is complete within 5 min. Cytochrome c complexed with DCH18C6 in the PEG-rich phase was quantitatively recovered into a salt-rich phase using K 2SO 4 by ion exchange of potassium ion and cationic protein in the cationic protein complex with DCH18C6. Selective extraction of cationic proteins was demonstrated in the ATPS. Under optimum conditions, the lysine-rich protein cytochrome c was selectively extracted over other cationic proteins using DCH18C6.

Diketopiperazine Supramolecule Derived from Hydroxyphenylglycine

A diketopiperazine (DKP) having long alkyl chains was synthesized from D-p-hydroxyphenylglycine, and the formation of supramolecules was examined. The 1 H NMR and UV-vis spectroscopic measurements and molecular modeling have suggested that the DKP molecules are aligned based on hydrogen bonding between the amide groups, and there is no stacking between the phenyl groups.

Porphyrin‐Based Nanostructures for Sensing Applications

The construction of nanosized supramolecular hosts via self‐assembly of molecular components is a fascinating field of research. Such intriguing class of architectures, beside their intrinsic intellectual stimuli, is of importance in many fields of chemistry and technology, such as material chemistry, catalysis, and sensor applications. Within this wide scenario, tailored solid films of porphyrin derivatives are structures of great potential for, among others, chemical sensor applications. The formation of supramolecules relays on noncovalent interactions (electrostatic, hydrogen bond, π‐π, or coordinative interactions) driven by the chemical information stored on the assembling molecules, such as shape and functional groups. This allows, for example, the formation of large well‐defined porphyrin aggregates in solution that can be spontaneously transferred onto a solid surface, so achieving a solid system with tailored features. These films have been used, covering the bridge between nanostructures and microsystems, for the construction of solid‐state sensors for volatiles and metal ion recognition and detection. Moreover, the variation of peripheral substituents of porphyrins, such as, for example, chiral appended functionalities, can result in the formation of porphyrin aggregates featuring high supramolecular chirality. This would allow the achievement of porphyrin layers characterised by different chiroptical and molecular recognition properties.

Lewis Acidic Behavior of Fluorinated Organomercurials

Owing to their unusual Lewis acidic properties, the coordination chemistry of fluorinated organomercurials is attracting increasing interest. In this review, the authors focus on the synthesis, structures, and properties of neutral Lewis adducts involving fluorinated organomercurials such as (CF3)2Hg, (C6F5)HgCl, (C6F5)2Hg, and [(o-C6F4)Hg]3. While most of these organomercurials form adducts with common Lewis basic organic substrates, [(o-C6F4)Hg]3 also interacts with aromatic hydrocarbons, alkynes, N-heterocycles, and metallocenes to form π-complexes. In some cases, this complexation mode results in the formation of supramolecules with unusual luminescence properties or microporosity.

Supramolecular systems of amphiphilic derivatives of calix[4]resorcinarenes and surfactants in chloroform

Aggregation of amphiphilic calix[4]resorcinarenes (CRA) modified by carboxymethyl (1), 2-hydroxyethyl (2), methylamino acetal (3), and aminomethyl (4) fragments and their interaction with some synthetic (5, 6) and natural (7, 8) surfactants in the low-polarity solvent (chloroform) were studied by permittivity measurements and FT-IR spectroscopy. Compounds 1–4 and surfactants form aggregates at critical micelle concentrations (CMC) of 2.0·10−5–7.5·10−5 and 1.7·10−5–2.0·10−3 mol L−1, respectively. The CMC values of CRA—surfactant mixed aggregates depend on the surfactant structure and the structure and concentration of CRA. Analysis of the IR spectra of solutions of a series of amphiphilic CRA (2–4, 9, 10) and their mixtures with the cationic surfactant N-cetyl-N,N-dimethyl-N-(2-hydroxyethyl)ammonium bromide (5) showed that an increase in the concentration of the solutions in individual and mixed systems is accompanied by a decrease in the molar integral intensities and intensities in the maxima of the absorption bands of the O—H and C—H bonds down to the CMC point, after which these values change slightly. The discovered effect, which is differently pronounced for all systems studied, indicates that both the polar “head” groups and nonpolar fragments of CRA and surfactant are involved in the formation of supramolecules of the reverse micelle type in all cases.

Heterologous gene expression using self-assembled supra-molecules with high affinity for HSP70 chaperone

Contrary to the results of direct expression, various human proteins (ferritin light-chain, epithermal growth factor, interleukin-2, prepro-ghrelin, deletion mutants of glutamate decarboxylase and arginine deiminase, and mini-proinsulin) were all soluble in Escherichia coli cytoplasm when expressed with the N-terminus fusion of ferritin heavy-chain (FTN-H). Through systematic investigations, we have found that a specific peptide motif within FTN-H has a high affinity to HSP70 chaperone DnaK, and that the peptide motif was composed of a hydrophobic core of three residues (Ile, Phe and Leu) and two flanking regions enriched with polar residues (Gly, Gln and Arg). It was also observed that all the recombinant proteins expressed with the fusion of FTN-H formed spherical nanoparticles with diameters of 10–15 nm, as confirmed by the transmission electron microscopy image. The protein nanoparticles are non-covalently cross-linked supra-molecules formed by the self-assembly function of FTN-H. Upon the formation of the supra-molecule, its size is likely to be limited by the assembly properties of FTN-H, thereby keeping the self-assembled particles soluble. This study reports on the dual function of FTN-H for fusion expression and solubility enhancement of heterologous proteins: (i) high-affinity interaction with DnaK and (ii) formation of self-assembled supra-molecules with limited and constant sizes, thereby avoiding the undesirable formation of insoluble macro-aggregates of heterologous proteins.

Polyfunctional molecules and their components in the processes of aromatic nucleophilic substitution. II. Nucleophilic modification of 3',5'-bis-O-(alpha,beta,alpha',beta'-tetrafluoropyridyl-gamma)thymidine

The interaction of 3',5'-bis-O-(alpha,beta,alpha',beta'-tetrafluoropyrid-gamma-yl)thymidine with various nucleophilic reagents was studied to evaluate the possibility of molecular design of new types of nucleic acid analogues using SNAr reactions. The reactions with morpholine and sodium azide led to the introduction of one and two nucleophilic residues into each of the polyfluorinated pyridine rings. The nucleophilic polycondensation with bifunctional reagents ethylenediamine and hexamethylenediamine depended on the nature of nucleophile and reaction conditions and resulted in the formation of supramolecules containing about five or more than 20 pyrimidine bases.

Supramolecular formation via hydrogen bonding in the Zn(II), Mn(II)and Cu(II) complexes with 3-hydroxypicolinic acid

The three new complexes, [Zn(picoH) 2·2H 2O] ( 1), [Mn(picoH) 2·2H 2O] ( 2) and [Cu(picoH) 2] ( 3) (HpicoH=3-hydroxypicolinic acid) were synthesized as single crystals by the hydrothermal reactions and characterized by single crystal X-ray diffraction, elemental analysis and thermal analysis. The complexes 1 and 2 are isomorphous and have rich hydrogen bonds formed by the coordinating water molecules with the carboxylate groups and the hydrogen atoms of the pyridine rings, respectively. The hydrogen bonds lead to the formation of supramolecules with three-dimensional network structures. In the crystal of the complex 3, the copper(II) ion is not only strongly coordinated by four atoms (N 2O 2) in a square-planar fashion, but also interacts weakly with other two oxygen atoms, forming a distorted octahedron. The coordination number of the copper(II) ion can be described as ‘4+2’. The weak Cu–O coordination bonds and hydrogen bonds in 3 bring the moieties into a supramolecule with three-dimensional network.

Effect of lanthanides on the spectral-luminescence properties and photoresistance of organic dyes in silicate sol-gel films

A sol-gel method is used to synthesize silicate films dyed in the sol stage with rhodamine C or methylene blue and further doped with cerium or lanthanum. It is shown that this sort of doping leads to a reduction in the peak intensity and a change in the shape of the S1←S0 band of the dyes, as well as to a shift in this band in a direction that depends on the H2O: Si(OC2H5)4 ratio. At the same time, the photoresistance of the rhodamine C molecules increases. The observed spectral changes are explained by the formation of supramolecules that include organic molecules, rare earth ions, and elements from the structural grid of the film, while the enhanced photoresistance is explained mainly by strengthening of the T1→S0 transitions in the dye.

Formation of supramolecules in solution. Interaction between transition-metal complexes and water-soluble porphyrins

The rates of copper(II) insertion into water-soluble porphyrins in the presence of ethylenediamine have been studied near pH 7. Unusual kinetic profiles result which are interpreted as arising from the formation of supramolecular assemblies in solution. Confirmatory evidence for this model is provided by light scattering, conductance and temperature-variation experiments. The influences on assembly formation of reactant concentration, porphyrin charge and basicity, ionic strength, as well as buffer and electrolyte identity are reported.