scholarly journals Seed geometry and hydrogen bonding dependent plasmonic tuning of silver nanocrystals in a citrate–hydrazine matrix and SERS spectroscopic detection of chromium

RSC Advances ◽  
2017 ◽  
Vol 7 (73) ◽  
pp. 45911-45919 ◽  
Author(s):  
Satarupa Pattanayak ◽  
Abhishek Swarnkar ◽  
Pradip Paik ◽  
Amiya Priyam
Keyword(s):  
Hydrogen Bonding ◽  
Spectroscopic Method ◽  
Blue Shift ◽  
Red Shift ◽  
Plasmonic Tuning

Red-shift and blue-shift in the plasmon wavelength has been observed depending on the seed geometry. Further, these Ag nanocrystals have been used to develop a SERS-spectroscopic method for enhanced detection of chromium upto a limit of 30 ppb.

Unusual spectral shifts in the prototropic reactions of 2,7-diaminofluorene

1987 ◽  
Vol 65 (9) ◽  
pp. 2013-2018 ◽  
Author(s):  
R. Manoharan ◽  
Sneh K. Dogra
Keyword(s):  
Absorption Spectrum ◽  
Aqueous Medium ◽  
Fluorescence Spectrum ◽  
Blue Shift ◽  
Proton Donor ◽  
Red Shift ◽  
The Other ◽  
Spectral Shifts ◽  
Other Hand

The red shift observed in the absorption spectrum of 2,7-diaminofluorene (DAF) in ether and acetonitrile is either due to the proton-donating capacity of the solute or due to its dispersive interactions with the solvent and a blue shift in methanol and water is due to the proton-accepting nature of DAF. DAF acts as a proton donor in S1 state in all solvents. The red shift in the fluorescence spectrum of the monocation of DAF relative to that of DAF is not because of the —NH2 group becoming more basic but because of the large solvent relaxating in aqueous medium. On the other hand, the monocation of DAF in cyclohexane follows the normal blue shift in the fluorescence spectrum. pKa values for the various prototropic reactions in S0 and S1 states are determined and discussed.

Investigation of the Effects of Various Cyclodextrins on the Stabilisation of Human Serum Albumin by a Spectroscopic Method

2015 ◽  
Vol 68 (12) ◽  
pp. 1894 ◽  
Author(s):  
Mohsen Oftadeh ◽  
Golamreza Rezaei Behbahani ◽  
Ali Akbar Saboury ◽  
Shahnaz Rafiei
Keyword(s):  
Human Serum Albumin ◽  
Serum Albumin ◽  
Human Serum ◽  
Electrostatic Interactions ◽  
Spectroscopic Method ◽  
Phosphate Buffer Solution ◽  
Blue Shift ◽  
Titration Calorimetry ◽  
Tryptophan Residue ◽  
Buffer Solution

The binding parameters between cyclodextrins (CDs) and human serum albumin (HSA) were investigated by isothermal titration calorimetry (ITC), fluorescence quenching, and UV-vis absorption spectroscopy at 300 K in 50 mM phosphate buffer solution. Among the various CDs investigated, β-CD has the greater ability to decrease the aggregation of HSA and the results indicated that the inhibition order is γ-CD < α-CD < β-CD. The obtained heats for HSA+CDs interactions were reported and analysed in terms of the extended solvation model, which was used to reproduce the enthalpies of HSA interactions with CDs over a broad range of complex concentrations. The binding constant and thermodynamic parameters were obtained. These suggested that the binding reaction was driven by both enthalpy and entropy, and electrostatic interactions played a major role in the stabilising of HSA. The parameters and reflected the net effect of β-CD on the HSA stability at low and high cyclodextrin concentrations, respectively. The positive values for indicated that β-CD stabilises the HSA structure at low concentrations. The UV absorption intensity of theses complexes increased and a slight red shift was observed in the absorbance wavelength with increasing the CD concentration. The fluorescence intensity of HSA decreased regularly and a slight blue shift was observed for the emission wavelength with increasing CD concentration. The results indicate that the CD complex could quench the fluorescence of HSA and changes the microenvironment of the tryptophan residue.

scholarly journals Impact of Solvents, Magnesium Oxide and Aluminium Oxide Nanoparticles on the Photophysical Properties of Acridine Orange Dye

2021 ◽  
pp. 1-7
Author(s):  
Fairooz Kareem ◽  
Mahasin Al-Kadhemy ◽  
Asrar Saeed
Keyword(s):  
Acridine Orange ◽  
Magnesium Oxide ◽  
Fluorescence Spectra ◽  
Aluminium Oxide ◽  
Blue Shift ◽  
Red Shift ◽  
Oxide Nanoparticles ◽  
Absorption And Fluorescence Spectra ◽  
Aluminium Oxide Nanoparticles ◽  
Al2o3 Nps

Absorption and fluorescence spectroscopy techniques were applied to investigate the photophysical characteristics of acridine orange (AO) dye in solvents that included distilled water, dimethyl sulfoxide (DMSO), acetone and ethanol in various concentrations (1×10-4–1×10-6) M. All of the samples were served at room temperature. The relationships between various parameters describing the strength of optical transitions in atoms and molecules were reviewed. This study expresses various viewpoints by describing how concentration and solvent affect the dye's absorption and fluorescence spectra. The absorption spectra of AO exhibit a band at (490 nm), except for DMSO, which shifts more towards red by 5 nm. The fluorescence spectra show a blue shift in AO aqueous solution around 6 nm until (0.5×10-4) M, followed by a red shift at around 7 nm at (1×10-6) M. There is a blue shift in (1×10-5) M for DMSO at around 4 nm, then a 10 nm red shift in higher concentrations as well as a 9 nm red shift in acetone and 6 nm in ethanol. Adding magnesium oxide nanoparticles (MgO NPs) quenched AO in both absorption and fluorescence spectra, whereas maximum fluorescence and intensity increased when aluminium oxide nanoparticles (Al2O3 NPs) were added to the solution. KEYWORDS Laser dye, absorption spectrum, fluorescence spectrum, MgO NPs, Al2O3 NPs

scholarly journals Interaction Mechanism between Antibiotics and Humic Acid by UV-Vis Spectrometry

2018 ◽  
Vol 15 (9) ◽  
pp. 1911 ◽  
Author(s):  
Xiaoyu Yuan ◽  
Shengke Yang ◽  
Jie Fang ◽  
Xueli Wang ◽  
Haizhen Ma ◽  
...  
Keyword(s):  
Humic Acid ◽  
Absorption Band ◽  
Interaction Mechanism ◽  
Blue Shift ◽  
Degree Of Polymerization ◽  
Ultraviolet Spectrum ◽  
Red Shift ◽  
Vis Spectroscopy ◽  
Nm Range ◽  
Peak Value

In this study, the interaction between the humus and two antibiotics was studied by UV-Vis spectroscopy to describe the interaction mechanism and the effects of different environmental factors on the mechanism. Results showed that humic acid (HA) containing more aromatic groups was easily associated with antibiotics. In the HA-OTC, with the increase of the concentration of OTC, there were obvious absorption peaks in the 230–260 nm and 330–360 nm range, and the absorption band of the HA ultraviolet spectrum underwent a slight blue shift and the absorption intensity increased, demonstrating that a new ground state complex was generated. In the HA-SD, with the increase of SD concentration, an aromatic structure absorption peak appeared in the 190–220 nm range, and the peak value increased and the absorption band underwent a red shift, and the aromatization of HA decreased, which enhanced the interaction between the antibiotics and HA. With the increase of pH, the absorption band of HA, HA-OTC and HA-SD ultraviolet spectrum suffered a blue shift, the degree of polymerization of HA molecules decreased, and the number of adsorption binding sites increased, which resulted in the interaction of HA with antibiotics being enhanced. The absorption band of HA, HA-OTC and HA-SD displayed a red shift with the increase of ionic strength, which indicated that the repulsion within HA particles was weakened, and the molecular polymerization was strengthened and therefore, the interaction between antibiotics and HA was inhibited. The UV characteristics of the HA, HA-OTC and HA-SD systems were insensitive to the temperature. This study lays the foundation for better studying the effect of humus on the distribution of antibiotic residues in the environment.

scholarly journals The Cruciality of Single Amino Acid Replacement for the Spectral Tuning of Biliverdin-Binding Cyanobacteriochromes

2020 ◽  
Vol 21 (17) ◽  
pp. 6278
Author(s):  
Keiji Fushimi ◽  
Hiroki Hoshino ◽  
Naeko Shinozaki-Narikawa ◽  
Yuto Kuwasaki ◽  
Keita Miyake ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Molecular Mechanisms ◽  
Near Infrared ◽  
Structural Characteristics ◽  
Blue Shift ◽  
Amino Acid Replacement ◽  
Red Shift ◽  
Single Amino Acid ◽  
Structural Basis ◽  
Small Unit

Cyanobacteriochromes (CBCRs), which are known as linear tetrapyrrole-binding photoreceptors, to date can only be detected from cyanobacteria. They can perceive light only in a small unit, which is categorized into various lineages in correlation with their spectral and structural characteristics. Recently, we have succeeded in identifying specific molecules, which can incorporate mammalian intrinsic biliverdin (BV), from the expanded red/green (XRG) CBCR lineage and in converting BV-rejective molecules into BV-acceptable ones with the elucidation of the structural basis. Among the BV-acceptable molecules, AM1_1870g3_BV4 shows a spectral red-shift in comparison with other molecules, while NpF2164g5_BV4 does not show photoconversion but stably shows a near-infrared (NIR) fluorescence. In this study, we found that AM1_1870g3_BV4 had a specific Tyr residue near the d-ring of the chromophore, while others had a highly conserved Leu residue. The replacement of this Tyr residue with Leu in AM1_1870g3_BV4 resulted in a blue-shift of absorption peak. In contrast, reverse replacement in NpF2164g5_BV4 resulted in a red-shift of absorption and fluorescence peaks, which applies to fluorescence bio-imaging in mammalian cells. Notably, the same Tyr/Leu-dependent color-tuning is also observed for the CBCRs belonging to the other lineage, which indicates common molecular mechanisms.

scholarly journals Investigation on the Influence of Microstructure Based on Hydrogen Bonding on Surface Tension by Raman Spectroscopy

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Nannan Wu ◽  
Shunli Ouyang ◽  
Junjie Cui ◽  
Shiliang Liu ◽  
Mingzhe Zhang ◽  
...  
Keyword(s):  
Surface Tension ◽  
Raman Spectroscopy ◽  
Hydrogen Bonding ◽  
Aqueous Solutions ◽  
Tracking System ◽  
Binary Solution ◽  
Spectroscopic Method ◽  
Mixed Solution ◽  
Direct Experiment ◽  
The Relationship

Surface tension (http://mts.hindawi.com/update/) in our Manuscript Tracking System and after you have logged in click on the ORCID link at the top of the page. This link will take you to the ORCID website where you will be able to create an account for yourself. Once you have done so, your new ORCID will be saved in our Manuscript Tracking System automatically."?>and Raman spectra containing hydrogen bonding in acetonitrile aqueous solutions with different mole ratios were obtained. Varied surface tension and hydrogen bonding in the mixed solution were discussed. For this purpose, the OH stretching bands were fitted into three Gaussian components to which different hydrogen-bonded water samples were assigned. Furthermore, the microstructures of binary solution were analyzed. The results indicated that the surface tension decreases dramatically with the enhancement of hydrogen bonds in the mixture. A spectroscopic method for studying the macroscopic properties of aqueous solutions was employed. The direct experiment results provided the relationship between surface tension and microstructure in aqueous solutions.

Effect of fast thermal annealing on the optical spectroscopy in MBE- and CBE-grown GaInNAs/GaAs QWs: blue shift versus red shift

2004 ◽  
Vol 151 (5) ◽  
pp. 284-289 ◽  
Author(s):  
N. Balkan ◽  
A. Erol ◽  
R.J. Potter ◽  
S. Mazzucato ◽  
C.J. Hepburn ◽  
...  
Keyword(s):  
Thermal Annealing ◽  
Optical Spectroscopy ◽  
Blue Shift ◽  
Red Shift

Effects of Cu Dopant on Lattice and Optical Properties of ZnS Quantum Dots

2016 ◽  
Vol 16 (4) ◽  
pp. 3816-3820
Author(s):  
Lu Shuhua ◽  
Wang Aiji ◽  
Chen Tingfang ◽  
Wang Yinshu
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Quantum Dot ◽  
Blue Shift ◽  
Red Shift ◽  
Colloidal Nanocrystals ◽  
Long Tail ◽  
Low Concentrations ◽  
Cu Dopant ◽  
Cu Ions

Doped and undoped ZnS colloidal nanocrystals have drawn much attention due to their versatile applications in the fields of optoelectronics and biotechnology. In this paper, Cu doped ZnS quantum dots were synthesized via the simple thermolysis of ethylxanthate salts. The lattice and optical properties of the nanocrystals were then studied in detail. The quantum dot lattice contracted linearly between Cu concentrations of 0.2–2%, while it continued to contract more gradually as Cu concentrations were further increased from 4 to 6%, due in part to the Cu ions located on the surface of the ZnS lattice. Cu incorporation induces a long tail in absorption at long wavelengths. The PL spectrum shows a red shift at first, and then a blue shift with increases in Cu concentration. Cu doped at low concentrations (0.2–1%) enhanced the emission, while high Cu concentrations (2–6%) quenched emissions.

Synthesis and Photophysical Properties of Side-Chain Polyfluorenes

2017 ◽  
Vol 865 ◽  
pp. 60-63
Author(s):  
Ning Wang ◽  
Xiao Dan Hu
Keyword(s):  
Solar Cells ◽  
Organic Solar Cells ◽  
Photophysical Properties ◽  
Gel Permeation Chromatography ◽  
Blue Shift ◽  
Red Shift ◽  
Side Chain ◽  
Gel Permeation

In this paper, we reported one vinylfluorene derivative 9,9-dihexyl-vinylfluorene and its corresponding polymers. The monomer and polymers were characterized by NMR, UV-Vis, PL and Gel Permeation Chromatography (GPC). Compared with the monomer, the polymers showed blue-shift in UV-Vis spectra but red-shift in PL spedtra. This kind of side-chain polyfluorenes could be candidates of blue OLED, organic solar cells, and so on.

Analysis of the Visual Spectrum of Methyl Orange in Solvents and in Hydrophobic Binding Sites

1973 ◽  
Vol 51 (4) ◽  
pp. 628-635 ◽  
Author(s):  
Richard L. Reeves ◽  
Robert S. Kaiser ◽  
Mary S. Maggio ◽  
Edward A. Sylvestre ◽  
William H. Lawton
Keyword(s):  
Hydrogen Bonding ◽  
Methyl Orange ◽  
Organic Solvents ◽  
Absorption Maximum ◽  
Low Frequency ◽  
Blue Shift ◽  
Frequency Component ◽  
High Frequency Component ◽  
Surfactant Micelle ◽  
Aqueous Solvent

The absorption curves of methyl orange (MO) and analogous p-aminophenylazobenzenes in organic and aqueous organic solvents are shown to consist of two severely overlapping bands. The curves have been resolved into two skewed component bands using a regression method. The blue shift of the absorption maximum obtained when organic solvents are added to aqueous solutions of MO, or when MO is bound to bovine serum albumin or a surfactant micelle, is the result of a change in relative intensities of the component bands. The low-frequency component is assigned to a π1 → π1* transition of a solvate in which there is specific hydrogen-bonding interaction between solvent and the azo nitrogens, and the high-frequency component to a π1 → π1* transition of a solvate in which the interaction is absent. The low-frequency component is favored by aqueous solvent compositions and by low temperatures. The free energies of interconversion of the species in various hydrogen-bonding solvents are correlated by the solvent surface tension but not by the dielectric constant. The results show that the shift in absorption maximum accompanying binding to a protein or micelle should be interpreted as a shift in an equilibrium rather than as a shift in transition energy.

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