scholarly journals 5-Ureido-3,3-diphenyl-3H-naphtho[2,1-b]pyrans: Photoswitchable self-assembling architectures

2004 ◽  
Vol 6 (4) ◽  
pp. 169-173 ◽  
Author(s):  
X. Sallenave ◽  
S. Delbaere ◽  
S. Ahmed ◽  
G. Vermeersch ◽  
J. L. Pozzo
Keyword(s):  
Carbonyl Group ◽  
Uv Irradiation ◽  
2D Nmr ◽  
Intramolecular Interactions ◽  
The Self ◽  
Visible Spectroscopy ◽  
Photochromic Properties ◽  
Self Assembling ◽  
Amino Derivatives ◽  
Uv Visible

5-Ureido-3,3-diphenyl-3H-naphtho[2,1-b]pyrans have been synthesized and their photochromic properties have been quantified using UV-Visible spectroscopy. The urea pattern is responsive for the selfassembling properties under both colourless and coloured forms whereas the corresponding amino derivatives do not show any aggregative properties. The geometries of the different states have been assigned using1Hand19FNMR spectroscopies, and thereafter their respective kind of aggregates could be proposed through the different inter- and intramolecular interactions. Upon UV irradiation, the pyranic ring is opened and the resulting photogenerated carbonyl group is competing with the urea in the self-assembling process and consequently strongly affects the supramolecular assemblies. The inter- and intramolecular contributions have been quantified through 1D and 2D NMR experiments along with the variation in the concentration.

Fluorescent Rosette Nanotubes from the C-analogue of the Guanine–Cytosine (G∧C) Motif

2015 ◽  
Vol 1796 ◽  
pp. 1-6 ◽  
Author(s):  
Belete Legesse ◽  
Jae-Young Cho ◽  
Rachel L. Beingessner ◽  
Takeshi Yamazaki ◽  
Hicham Fenniri
Keyword(s):  
Electron Microscopy ◽  
Self Assembly ◽  
The Self ◽  
Visible Spectroscopy ◽  
Fluorescent Properties ◽  
Force Microscopy ◽  
Rosette Nanotubes ◽  
Atomic Force ◽  
Transmission Electron ◽  
Uv Visible

ABSTRACTRosette nanotubes (RNTs) are tubular architectures generated through the hierarchical self-assembly of the guanine-cytosine (G∧C) motif 1 or 2 (Figure 1). Motif 2 differs from 1 by the substitution at the N-atom in the G-ring with a C-atom as shown in red. In this paper, we prepare a new tricyclic G∧C base 3 from a functionalized derivative of 2 and demonstrate its self-assembly into fluorescent helical RNTs in N,N-dimethylformamide (DMF). The self-assembly and fluorescent properties of RNTs 3 were established using scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM) and UV-visible spectroscopy.

Interaction of diatomic ligands with Fe(II) meso-mono-4-pyridyl-tri-phenyl-porphyrinate. Spectral evidence of self-assembly in sublimed layers

2003 ◽  
Vol 07 (09) ◽  
pp. 623-629 ◽  
Author(s):  
Tigran S. Kurtikyan ◽  
J. Steven Ogden ◽  
Robert K. Kazaryan ◽  
Valery N. Madakyan
Keyword(s):  
Low Temperature ◽  
Self Assembly ◽  
Thin Layers ◽  
The Self ◽  
Ambient Conditions ◽  
Visible Spectroscopy ◽  
Pyridyl Group ◽  
Sublimed Layers ◽  
Uv Visible ◽  
Adjacent Molecule

The interaction of CO , NO and O2 gases with thin layers of meso-mono-4-pyridyl-tri-phenylporphyrinatoiron(II) ( FeMPyTPP ) obtained by sublimation onto low-temperature (T = 77 K ) substrates has been investigated by means of IR and UV-visible spectroscopy. In contrast to the closely-related meso-tetraphenylporphyrinatoiron(II) ( FeTPP ), the formation of two types of axial complexes has been observed. In one of these the 5th coordination site is occupied by the pyridyl group of an adjacent molecule indicating the self-assembly of Fe ( MPyTPP ) in layers with formation of coordinatively linked oligomers. The degree of oligomerisation depends on the nature of the interacting gas. Due to the specificity of the supramolecular structure, the layers are fairly stable in ambient conditions and conserve their microporosity to bind reversibly with the aforementioned ligands.

scholarly journals Solid-state optical properties of self-assembling amyloid-like peptides with different charged states at the terminal ends

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Chiara Schiattarella ◽  
Carlo Diaferia ◽  
Enrico Gallo ◽  
Bartolomeo Della Ventura ◽  
Giancarlo Morelli ◽  
...  
Keyword(s):  
Solid State ◽  
Charge State ◽  
Spectroscopic Properties ◽  
The Self ◽  
Quantum Yields ◽  
Visible Range ◽  
Small Peptides ◽  
Self Assembling ◽  
Uv Visible ◽  
Pl Emission

AbstractThe self-assembling of small peptides not only leads to the formation of intriguing nanoarchitectures, but also generates materials with unexpected functional properties. Oligopeptides can form amyloid-like cross-β assemblies that are able to emit intrinsic photoluminescence (PL), over the whole near-UV/visible range, whose origin is still largely debated. As proton transfer between the peptide chain termini within the assembly is one of the invoked interpretations of this phenomenon, we here evaluated the solid state PL properties of a series of self-assembled hexaphenylalanine peptides characterized by a different terminal charge state. Overall, our data indicate that the charge state of these peptides has a marginal role in the PL emission as all systems exhibit very similar multicolour PL associated with a violation of the Kasha’s rule. On the other hand, charged/uncharged ends occasionally produce differences in the quantum yields. The generality of these observations has been proven by extending these analyses to the Aβ16–21 peptide. Collectively, the present findings provide useful information for deciphering the code that links the spectroscopic properties of these assemblies to their structural/electronic features.

The Investigation of the Neopluramycin � DNA System by UV-visible Spectroscopy

2008 ◽  
Vol 59 (9) ◽  
Author(s):  
Loredana Elena V�jan
Keyword(s):  
Absorption Coefficient ◽  
Binding Constant ◽  
The Self ◽  
Molar Absorption Coefficient ◽  
Water Mixture ◽  
Visible Spectroscopy ◽  
Dimerization Constant ◽  
Calf Thymus ◽  
Uv Visible ◽  
Self Association

The self-association of neopluramycin and the binding of this drug to calf thymus DNA were investigated by using UV-visible spectroscopy. This classical pluramycin antibiotic self-associates in 1:1 ethanol - water mixture. Starting from a simple dimerization model, the molar absorption coefficient of monomer, the molar absorption coefficient of dimer and the dimerization constant were determined. The binding constant of neopluramycin to DNA was determined using Wolfe and Scatchard methods.

scholarly journals Solid-State Optical Properties of Self-Assembling Amyloid-Like Peptides with Different Charged States at the Terminal Ends

2021 ◽  
Author(s):  
Chiara Schiattarella ◽  
Carlo Diaferia ◽  
Enrico Gallo ◽  
Bartolomeo Della Ventura ◽  
Giancarlo Morelli ◽  
...  
Keyword(s):  
Solid State ◽  
Charge State ◽  
Spectroscopic Properties ◽  
The Self ◽  
Quantum Yields ◽  
Visible Range ◽  
Small Peptides ◽  
Self Assembling ◽  
Uv Visible ◽  
Pl Emission

Abstract The self-assembling of small peptides not only leads to the formation of intriguing nanoarchitectures, but also generates materials with unexpected functional properties. Oligopeptides can form amyloid-like cross-β assemblies that are able to emit intrinsic photoluminescence (PL), over the whole near-UV/visible range, whose origin is still largely debated. As proton transfer between the peptide chain termini within the assembly is one of the invoked interpretations of this phenomenon, we here evaluated the solid state PL properties of a series of self-assembled hexaphenalanine peptides characterized by a different terminal charge state. Overall, our data indicate that the charge state of these peptides has a marginal role in the PL emission as all systems exhibit very similar multicolour PL associated with a violation of the Kasha’s rule. On the other hand, charged/uncharged ends occasionally produce differences in the quantum yields. The generality of these observations has been proven by extending these analyses to the Aβ16−21 peptide. Collectively, the present findings provide useful information for deciphering the code that links the spectroscopic properties of these assemblies to their structural/electronic features.

scholarly journals Synthesis, Characterization and Anticancer Activity of Porphyrin-Containing Organometallic Cubes

2010 ◽  
Vol 63 (11) ◽  
pp. 1529 ◽  
Author(s):  
Nicolas P. E. Barry ◽  
Olivier Zava ◽  
Paul J. Dyson ◽  
Bruno Therrien
Keyword(s):  
Mass Spectrometry ◽  
Cell Viability ◽  
Anticancer Activity ◽  
Cancer Cells ◽  
Drug Concentration ◽  
Self Assembly ◽  
The Self ◽  
Visible Spectroscopy ◽  
Silver Triflate ◽  
Uv Visible

Self‐assembly of 5,10,15,20‐tetra(4‐pyridyl)porphyrin (tpp‐H2) and 5,10,15,20‐tetra(4‐pyridyl)porphyrin‐M(ii) (M = Ni (tpp‐Ni); Zn (tpp‐Zn)) tetradentate panels with the dinuclear p‐cymene ruthenium clips [Ru2(p-cymene)2(C2O4)Cl2] and [Ru2(p-cymene)2(C6H2O4)Cl2] (C2O4 = oxalato; C6H2O4 = 2,5‐dioxydo‐1,4‐benzoquinonato) affords the cationic organometallic cubes: [Ru8(p-cymene)8(tpp‐H2)2(C2O4)4]8+ (1); [Ru8(p-cymene)8(tpp‐Ni)2(C2O4)4]8+ (2); [Ru8(p-cymene)8(tpp‐Zn)2(C2O4)4]8+ (3); [Ru8(p-cymene)8(tpp‐H2)2(C6H2O4)4]8+ (4); [Ru8(p-cymene)8(tpp‐Ni)2(C6H2O4)4]8+ (5); and [Ru8(p-cymene)8(tpp‐Zn)2(C6H2O4)4]8+ (6). In addition, the new dinuclear arene ruthenium 2,5‐dioxydo‐1,4‐benzoquinonato clips [Ru2(indane)2(C6H2O4)Cl2] (7) and [Ru2(nonylbenzene)2(C6H2O4)Cl2] (8) react in methanol with tpp‐H2 in the presence of silver triflate to afford the corresponding cationic cubes [Ru8(indane)8(tpp‐H2)2(C6H2O4)4]8+ (9) and [Ru8(nonylbenzene)8(tpp‐H2)2(C6H2O4)4]8+ (10) respectively. All cationic metalla‐cubes were isolated as triflate salts and characterized by NMR, infrared, electro‐spray mass spectrometry and UV‐visible spectroscopy. Moreover, the formation of unsymmetrical metalla‐cubes built using a mixture of the different porphyrin panels during the self‐assembly of the 2,5‐dioxydo‐1,4‐benzoquinonato metalla‐cubes, [Ru8(p-cymene)8(tpp‐H2)(tpp‐Ni)(C6H2O4)4]8+ (11), [Ru8(p-cymene)8(tpp‐H2)(tpp‐Zn)(C6H2O4)4]8+ (12), and [Ru8(p-cymene)8(tpp‐Ni)(tpp‐Zn)(C6H2O4)4]8+ (13), was studied by electro‐spray mass spectrometry. The cytotoxicities of all metalla‐cubes as well as the mixtures containing the unsymmetrical metalla‐cubes were established on human ovarian A2780 and A2780cisR cancer cell lines. All symmetrical compounds are equally cytotoxic (IC50 = 7–15 μM) (IC50 being the drug concentration necessary for 50% inhibition of cell viability) against both A2780 and cisplatin‐resistant A2780cisR cancer cells, with stronger cytotoxicities (IC50 = 2–5 μM) observed for the mixtures containing the unsymmetrical 2,5‐dioxydo‐1,4‐benzoquinonato metalla‐cubes.

Biocompatibility of Silver Nano Bio-conjugates from Vitis vinifera Seeds and its Major Component Resveratrol

2016 ◽  
Vol 6 (3) ◽  
Author(s):  
R. Preethi ◽  
P. Padma
Keyword(s):  
Zeta Potential ◽  
Vitis Vinifera ◽  
Silver Ions ◽  
Seed Extract ◽  
Polydispersity Index ◽  
Potential Range ◽  
Visible Spectroscopy ◽  
Grape Seeds ◽  
X Ray ◽  
Uv Visible

The study focused on the green synthesis of silver nanobioconjugates (AgNPs) from phenolic-rich fruit source, Vitis vinifera seed extract and its major component phenolic, resveratrol respectively. Sunlight exposure for 20 minutes was the method of choice for the synthesis of AgNPs of the extract as well as the phenolic, resveratrol. The synthesized nanobioconjugates were characterized using UV-Visible spectroscopy, Transmission electron microscopy (TEM), Energy dispersive X-ray analysis (EDAX), X-ray diffraction (XRD), Polydispersity index, Zeta potential and Fourier transform infrared spectroscopy (FTIR). The reduction of silver ions was confirmed by UV-visible spectroscopy with peaks at 440nm for both nanobioconjugates synthesized from seed extract and compound. The nanobioconjugates showed the spherical in shape with 14-35nm in size and crystalline in nature. The conjugates are well dispersed with 0.301 and 0.287 polydispersity index and the zeta potential range at -13.6 and -14.3mV for stability. The FTRI data proved that the components in grape seeds act as good reductants and stabilizers for the silver nanobioconjugate synthesis. All the synthesized nanobioconjugates exhibited steady and sustained release of the medicinal components conjugated, proving their druggability, and were biocompatible with human cells, demonstrating their safety. The findings of the study validate the anticancer properties of silver nanobioconjugates of Vitis vinifera and its active component resveratrol.

Evaluation of Antibacterial and Antidiabetic Potential of Silver Nanoparticles using Eugenia Uniflora L. Seed Extract

2020 ◽  
Vol 13 (6) ◽  
pp. 5217-5225
Author(s):  
Guru Kumar Dugganaboyana ◽  
Chethankumar Mukunda ◽  
Suresh Darshini Inakanally
Keyword(s):  
Biomedical Applications ◽  
Pathogenic Bacteria ◽  
Seed Extract ◽  
Drug Formulation ◽  
Visible Spectroscopy ◽  
Plant Materials ◽  
X Ray ◽  
Eugenia Uniflora ◽  
Uv Visible

In recent years, green nanotechnology-based approaches using plant materials have been accepted as an environmentally friendly and cost-effective approach with various biomedical applications. In the current study, AgNPs were synthesized using the seed extract of the Eugenia uniflora L. (E.uniflora). Characterization was done using UV-Visible spectroscopy, X-ray diffraction (XRD), scanning electronic microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) analyses. The formation of AgNPs has confirmed through UV-Visible spectroscopy (at 466 nm) by the change of color owing to surface Plasmon resonance. Based on the XRD pattern, the crystalline property of AgNPs was established. The functional group existing in seed of E.uniflora extract accountable for the reduction of Ag+ ion and the stabilization of AgNPs was investigated. The morphological structures and elemental composition was determined by SEM and EDX analysis. With the growing application of AgNPs in biomedical perspectives, the biosynthesized AgNPs were evaluated for their antibacterial and along with their antidiabetic potential. The results showed that AgNPs are extremely effective with potent antidiabetic potential at a very low concentration. It also exhibited potential antibacterial activity against the three tested human pathogenic bacteria. Overall, the results highlight the effectiveness and potential applications of AgNPs in biomedical fields such as in the treatment of acute illnesses as well as in drug formulation for treating various diseases such as cancer and diabetes. It could be concluded that E. uniflora seed extract AgNPs can be used efficiently for in vitro evaluation of their antibacterial and antidiabetic effects with potent biomedical applications.

Directive Effect of Chain Length in Modulating Peptide Nano-assemblies

2020 ◽  
Vol 27 (9) ◽  
pp. 923-929
Author(s):  
Gaurav Pandey ◽  
Prem Prakash Das ◽  
Vibin Ramakrishnan
Keyword(s):  
Electron Microscopy ◽  
Amino Acids ◽  
Light Scattering ◽  
Chain Length ◽  
Self Assembly ◽  
The Self ◽  
Ionic Charge ◽  
Self Assembling ◽  
Biophysical Techniques

Background: RADA-4 (Ac-RADARADARADARADA-NH2) is the most extensively studied and marketed self-assembling peptide, forming hydrogel, used to create defined threedimensional microenvironments for cell culture applications. Objectives: In this work, we use various biophysical techniques to investigate the length dependency of RADA aggregation and assembly. Methods: We synthesized a series of RADA-N peptides, N ranging from 1 to 4, resulting in four peptides having 4, 8, 12, and 16 amino acids in their sequence. Through a combination of various biophysical methods including thioflavin T fluorescence assay, static right angle light scattering assay, Dynamic Light Scattering (DLS), electron microscopy, CD, and IR spectroscopy, we have examined the role of chain-length on the self-assembly of RADA peptide. Results: Our observations show that the aggregation of ionic, charge-complementary RADA motifcontaining peptides is length-dependent, with N less than 3 are not forming spontaneous selfassemblies. Conclusion: The six biophysical experiments discussed in this paper validate the significance of chain-length on the epitaxial growth of RADA peptide self-assembly.

A Solvent-Dependent and Electrochemically Controlled Self-Assembling/Disassembling System

2003 ◽  
Vol 68 (9) ◽  
pp. 1647-1662 ◽  
Author(s):  
Valeria Amendola ◽  
Massimo Boiocchi ◽  
Yuri Diaz Fernandez ◽  
Carlo Mangano ◽  
Piersandro Pallavicini
Keyword(s):  
Equilibrium Mixture ◽  
Bidentate Ligand ◽  
Molecular Structures ◽  
The Self ◽  
Molar Ratio ◽  
Crystal And Molecular Structures ◽  
Self Assembling ◽  
Irreversible Oxidation ◽  
Irreversible Reduction ◽  
Metal Ligand

The bis-bidentate ligand R,S-1,2-diphenyl-N,N'-bis(2-quinolinemethylidene)ethane-1,2-diamine (ligand 4), containing two (iminomethyl)quinoline moieties separated by a cis-1,2-diphenylethylene spacer, forms stable complexes with both CuI and CuII. With CuII, the monomeric 1:1 complex [CuII(4)]2+ is obtained both in CH3CN and CH2Cl2. With CuI and overall 1:1 metal/ligand molar ratio, an equilibrium mixture is obtained in CH3CN, consisting of [CuI(4)2]+, [CuI2(4)2]2+ and [CuI2(4)(CH3CN)4]2+. The preponderant species is the two-metal one-ligand "open" complex [CuI2(4)(CH3CN)4]2+, in which each Cu+ cation is coordinated in a tetrahedral fashion by one (iminomethyl)quinoline unit and by two CH3CN molecules. Precipitation from the equilibrium mixture yields only crystals of [CuI2(4)(CH3CN)4](ClO4)2·2CH3CN, whose crystal and molecular structures have been determined. On the other hand, in the poorly coordinating CH2Cl2 solvent, only the dimeric helical [CuI2(4)2]2+ complex is obtained, when the overall metal/ligand 1:1 molar ratio is chosen. Addition of large quantities of acetonitrile to solutions of [CuI2(4)2]2+ in dichlorometane results in the formation of [CuI2(4)(CH3CN)4]2+, i.e. in the solvent-driven disassembling of the CuI helicate. While electrochemistry in CH3CN is poorly defined due to the presence of more than one CuI species, cyclic voltammetry experiments carried out in CH2Cl2 revealed a well defined behavior, with irreversible oxidation of [CuI2(4)2]2+ and irreversible reduction of [CuII(4)]2+ taking place at separate potentials (∆E ≈ 700 mV). Irreversibility and separation of the redox events are due to the self-assembling and disassembling processes following the reduction and oxidation, respectively.

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