Comparative FTIR spectroscopic investigation of N-H···O and N-H···π hydrogen bonding of selected N-substituted amides···

U ovom radu korišcen je spektroskopski, teorijski i hemometrijski pristup proucavanju N-HO i N-H··· vodonicne veze koja se uspostavlja izmedu amidnog protona i etarskog kiseonika tj aromaticnog sistema. U ovom radu odredeni su parametri N-HO i N-H vodonicne veze za šesnaest Nsupstituisanih amida sa tetrahidrofuranom i toluenom. Vecina ispitivanih amida do sada nije bila izucavana sa stanovišta vodonicne veze. Uspostavljene su korelacije izmedu spektorsopskih i teorijskih parametara. Izvršeno je poredenje medu osobinama vodonicno vezanih kompleksa za razlicite amide kao proton donore. Svih 32 ispitivanih vodonicno vezanih kompleksa okarakterisano je hemometrijskim metodama: Klaster analizom i analizom glavne komponente, na osnovu spektroskopskih, teorijskih i Taftovih parametaraIn this PhD thesis, N-H×××O and N-H··· hydrogen bond beetwen the amide proton with ether oxygen and aromatic system has been investigated using the spectroscopic and theoretical approach. The study included sixteen N-substituted amides (formamides, acetamides, caproamides and benzamides) as well as tetrahydrofuran and toluene. The possibility of using chemometric methods was investigated in order to characterise N-H...O and N-H··· hydrgen bonded complexes. Hierarchial clustering and Principal Component Analysis (PCA) have been applied on infrared spectroscopic, PM3 theoretical and Taft parameters of 32 Nsubstituted amide complexes with tetrahydrofuran and toluen

Chemometric characterization of the hydrogen bonding complexes of secondary amides and aromatic hydrocarbons

The paper reports the results of the study of hydrogen bonding complexes between secondary amides and various aromatic hydrocarbons. The possibility of using chemometric methods was investigated in order to characterize N-H•••π hydrogen bonded complexes. Hierarchical clustering and Principal Component Analysis (PCA) have been applied on infrared spectroscopic and Taft parameters of 43 N-substituted amide complexes with different aromatic hydrocarbons. Results obtained in this report are in good agreement with conclusions of other spectroscopic and thermodynamic analysis

Temperature imposed textural and surface synergism affecting the isomerization activity of sulfated zirconia catalysts

Using sulfuric acid as the sulfating agent, two catalyst series were obtained from hydroxide and nitrate precursor with a sulfate loading identical to commercial sulfated hydroxide, i.e., 4.2 mass %. After calcination at 500, 600 and 700 °C, all nine samples had various contents of residual sulfates depending on the origin of the catalyst. Accordingly, their surface properties were different, which, together with various textural properties, govern the formation of the active phase and their catalytic activity in the n-hexane isomerization reaction. The dominant activity and yield of mainly mono-branched isomers were attained in reaction at 200 °C with a commercially sulfated zirconia catalyst calcined at 500 °C. Among the SZ catalyst series synthesized from hydroxide and nitrate, the second according to its activity profile was similar to that of the commercially sulfated one, while samples originating from hydroxide showed some activity only after calcination at 600 °C. This is due to the poorer textural properties of the hydroxide series, necessitating a higher calcination temperature in order to promote the simultaneous decomposition of S-containing species and their re-adsorption into the zirconia matrix following interaction and active phase formation. It seems that the tetragonal zirconia phase was not responsible for the catalytic activity but a synergistic effect of the textural properties of the samples and the sulfate loadings, which determine different acid strengths on the catalyst surface

Mixed-monolayer functionalized gold nanoparticles for cancer treatment: Atomistic molecular dynamics simulations study.

Gold nanoparticles (AuNPs) are employed as drug carriers due to their inertness, non-toxicity, and ease of synthesis. An experimental search for the optimal AuNP design would require a systematic variation of physico-chemical properties which is time-consuming and expensive. Computational methods provide quicker and cheaper approach to complement experiments and provide useful guidelines. In this paper, we performed atomistic molecular dynamics simulations to study how the size, hydrophobicity, and concentration of the drug affect the structure of functionalized AuNPs in the aqueous environment. We simulated two groups of nano-systems functionalized with a zwitterionic background ligand, and a ligand carrying a drug (Quinolinol or Panobinostat). Results indicate that in the case of a hydrophobic drug (Quinolinol), the hydrophobicity drives the conformation changes of the coating layer. The tendency of the hydrophobic drug to reduce its solvent-accessible surface results in a decrease of the coating thickness and the overall NP size. Although the amount of accessible drug can be increased by increasing its initial concentration, it will compromise the solubility of the system. In the case of a hydrophilic drug (Panobinostat), the ligand in excess has a dominant influence on the final structure of the coating conformations. The percentage of accessible drug is significantly higher than in the hydrophobic systems for any given ratio. It implies that for hydrophilic systems we can generally expect higher biological efficiency. Our results highlight the importance of taking into account physico-chemical properties of drugs and ligands when developing gold-based nanosystems, especially in the case of hydrophobic drugs

Etching of Uncompensated Convex Corners with Sides along <n10> and <100> in 25 wt% TMAH at 80 °C

This paper presents etching of convex corners with sides along and crystallographic directions in a 25 wt% tetramethylammonium hydroxide (TMAH) water solution at 80 °C. We analyzed parallelograms as the mask patterns for anisotropic wet etching of Si (100). The sides of the parallelograms were designed along and crystallographic directions (1 and crystallographic directions were smaller than 45°. All the crystallographic planes that appeared during etching in the experiment were determined. We found that the obtained types of 3D silicon shape sustain when n > 2. The convex corners were not distorted during etching. Therefore, no convex corner compensation is necessary. We fabricated three matrices of parallelograms with sides along crystallographic directions and as examples for possible applications. Additionally, the etching of matrices was simulated by the level set method. We obtained a good agreement between experiments and simulations

Evolution of Si Crystallographic Planes-Etching of Square and Circle Patterns in 25 wt % TMAH

Squares and circles are basic patterns for most mask designs of silicon microdevices. Evolution of etched Si crystallographic planes defined by square and circle patterns in the masking layer is presented and analyzed in this paper. The sides of square patterns in the masking layer are designed along predetermined crystallographic directions. Etching of a (100) silicon substrate is performed in 25 wt % tetramethylammonium hydroxide (TMAH) water solution at the temperature of 80 °C. Additionally, this paper presents three-dimensional (3D) simulations of the profile evolution during silicon etching of designed patterns based on the level-set method. We analyzed etching of designed patterns in the shape of square and circle islands. The crystallographic planes that appear during etching of 3D structures in the experiment and simulated etching profiles are determined. A good agreement between dominant crystallographic planes through experiments and simulations is obtained. The etch rates of dominant exposed crystallographic planes are also analytically calculated

Uticaj modifikacije na strukturna, teksturalna i adsorpciona svojstva bentonita

Natural bentonite clay from the Bogovina locality in Serbia was Na-exchanged and modified using hexadecyll-trimethylammonium bromide as surfactant and organobentonite was obtained. The influence of modifications on the structural, textural and sorption properties of bentonite was investigated. It was estimated that modifications solely replace exchangeable cations in smectite layers, whereas other admixture minerals (quartz, calcite, feldspar) in bentonite remain unaffected. According to X-ray results the modification lead to changes in the smectite structure by either decreasing, for Na-bentonite, or increasing, for organobentonite, the interplanar spacing, d(001). The appearance of three new bands in IR spectra of HDTMA-bentonite comparing to those of raw and Na-bentonite assigned to the methylene vibrations confirmed the embedding of aliphatic cations into smectite structure. In organobentonite a significant change in textural properties was observed. In particular, specific surface area dramatically decreased while originally meso and microporous material became almost completely non-porous. Despite almost insignificant specific surface area the synthesized organobentonite due to gained organophyllity of its surface exhibits exquisite adsorption properties toward investigated textile dyes having adsorption capacity approx. 2 times higher than activated carbon.Prirodna bentonitna glina sa lokaliteta Bogovina u Srbiji je natrijumski izmenjena i modifikovana heksadeciltrimetil amonijum-bromidom kao surfaktantom, pri čemu je dobijen organobentonit. Ispitivan je uticaj modifikacije na strukturu, teksturalna i adsorpciona svojstva bentonita. Utvrđeno je da primenjeni postupci modifikacije dovode isključivo do izmene katjona u medulamelamom sloju smektita, dok modifikacija ne deluje na druge prateće minerale u bentonitu (kvare, kalcit, feldspat). Uprkos neznatnoj specifičnoj površini sintetizovani organobentonit zahvaljujući novodobijenoj organofilnosti površine pokazuje izuzetna adsorpciona svojstva prema tekstilnim bojama, imajući adsorpcioni kapacitet oko 2 puta veći od aktivnog uglja

Etched Parallelogram Patterns with Sides Along <100> and <n10> Directions in 25 wt % TMAH

In this paper, we present and analyze etching of parallelogram patterns in the masking layer on a (100) silicon in 25 wt % TMAH water solution at the temperature of 80 0C. Sides of parallelogram islands in the masking layer are designed along and crystallographic directions. A 3D simulation of the profile evolution from these patterns during etching of silicon using the level set method is also presented. We determined all crystallographic planes that appear during etching in the experiment and obtained simulated etching profiles of these 3D structures. A good agreement between dominant crystallographic planes through experiments and simulations is obtained

DUV fluorescence bioimaging study of the interaction of partially reduced graphene oxide and liver cancer cells

The interaction of partially reduced graphene oxide (prGO) and Huh7.5.1 liver cancer cells was investigated by means of DUV fluorescence bioimaging. The prGO sample was obtained by the reduction (to a certain extent) of the initially prepared graphene oxide (GO) nanosheets with hydrazine. The fluorescence of the GO nanosheets increases with time of the reduction due to a change in ratio of the sp(2) and sp(3) carbon sites and the prGO sample was extracted from the dispersion after 6 min, when the intensity of the fluorescence reached its maximum. The reduction process was left to proceed further to saturation until highly reduced graphene oxide (denoted here as rGO) was obtained. GO, prGO and rGO samples were investigated by structural (scanning electron microscopy (SEM), scanning transmission electron microscopy coupled with energy dispersive spectrometry (STEM-EDS)) and spectroscopic (UV-vis, photoluminescence (PL), Raman) methods. After that, Huh7.5.1 cells were incubated with GO, prGO and rGO nanosheets and used in bioimaging studies, which were performed on DISCO beamline of synchrotron SOLEIL. It was found that the prGO significantly enhanced the fluorescence of the cells and increased the intensity of the signal by similar to 2.5 times. Time-lapse fluorescence microscopy experiments showed that fluorescence dynamics strongly depends on the type of nanosheets used. The obtained prGO nanostructure can be easily conjugated with aromatic ring containing drugs, which opens a possibility for its applications in fluorescence microscopy monitored drug delivery