Background defining during the imine formation reaction in FT-IR liquid cell

Post-synthetic molecular modifications based on Schiff base condensation reactions for designing functional paddlewheel diruthenium(II,II) complexes

A new synthetic route for constructing functional paddlewheel diruthenium(II,II) complexes ([RuII,II2]) was developed by utilizing Schiff base condensation reactions of formyl-substituted benzoate-bridged [RuII,II2] complexes with various aromatic monoamines under mild conditions. Cyclic voltammetry and DFT calculations revealed that the attached Schiff base groups significantly affected the electronic states of the resulting [RuII,II2] complexes.

Dynamic Imine Bonding Facilitates Mannan Release from a Nanofibrous Peptide Hydrogel

Recently, there has been increased interest in using mannan as an immunomodulatory bioconjugate. Despite notable immunological and functional differences between the reduced (R-Man) and oxidized (O-Man) forms of mannan, little is known about the impact of mannan oxidation state on its in vivo persistence or its potential controlled release from biomaterials that may improve immunotherapeutic or prophylactic efficacy. Here, we investigate the impact of oxidation state on the in vitro and in vivo release of mannan from a biocompatible and immunostimulatory multidomain peptide hydrogel, K2(SL)6K2 (abbreviated as K2), that has been previously used for the controlled release of protein and small molecule payloads. We observed that O-Man released more slowly from K2 hydrogels in vitro than R-Man. In vivo, the clearance of O-Man from K2 hydrogels was slower than O-Man alone. We attributed the slower release rate to the formation of dynamic imine bonds between reactive aldehyde groups on O-Man and the lysine residues on K2. This imine interaction was also observed to improve K2 + O-Man hydrogel strength and shear recovery without significantly influencing secondary structure or peptide nanofiber formation. There were no observed differences in the in vivo release rates of O-Man loaded in K2, R-Man loaded in K2, and R-Man alone. These data suggest that, after subcutaneous injection, R-Man naturally persists longer in vivo than O-Man and minimally interacts with the peptide hydrogel. These results highlight a potentially critical, but previously unreported, difference in the in vivo behavior of O-Man and R-Man and demonstrate that K2 can be used to normalize the release of O-Man to that of R-Man. Further, since K2 itself is an adjuvant, a combination of O-Man and K2 could be used to enhance the immunostimulatory effects of O-Man for applications such as infectious disease vaccines and cancer immunotherapy.

High temperature ATR-FTIR characterization of the interaction of polycarboxylic acids and organotrialkoxysilanes with cellulosic material

To convey novel properties to textile surface cotton-based fabrics were impregnated with solutions containing various chemical agents, such as butane-1,2,3,4-tetracarboxylic acid or hydrolyzed organotrialkoxysilanes (3-amino)propyltriethoxysilane), (3-glycidylpropyl)-trimethoxysilane, (3-triethoxysilylpropyl)succinic acid anhydride, octyltriethoxysilane, and Dynasylan F8815 (fluoroalkylfunctional water-borne oligosiloxane). The as-prepared cotton specimens were dried and cured at elevated temperatures. As the curing process can be performed at different temperatures, the impregnated and dried cotton samples were studied by means of time-dependent ATR-FTIR spectroscopy in an attempt to get a closer insight into the process mechanism. The results make evident that the butane-1,2,3,4-tetracarboxylic acid and (3-triethoxysilylpropyl)succinic acid anhydride reacts with the hydroxyl groups of the cellulose via a five-membered cyclic anhydride intermediate which is confirmed by vibration bands appearing at 1782 cm^-1 (symmetric stretching vibration of the anhydride carbonyl group) and at 1861 cm^-1 (antisymmetric stretching vibration of the anhydride carbonyl group).

Facile fabrication of a heterogeneous Co-modified pyridinecarboxaldehyde-polyethylenimine catalyst for efficient CO2 conversion under mild conditions

A heterogeneous Co-modified pyridinecarboxaldehyde-polyethylenimine catalyst with active metal sites and amine groups exhibited high catalytic activity for CO₂ conversion under mild conditions, even at ambient temperature.

Synthesis of quinolines from aniline and propanol over modified USY zeolite: catalytic performance and mechanism evaluated by in situ Fourier transform infrared spectroscopy

Synthetic passway of quinolines from aniline and propanol over modified USY catalyst.

Investigation of Possible Maillard Reaction Between Acyclovir and Dextrose upon Dilution Prior to Parenteral Administration

In this study the stability of parenteral acyclovir (ACV) when diluted in dextrose (DEX) as large volume intravenous fluid preparation (LVIF) was evaluated and the possible Maillard reaction adducts were monitored in the recommended infusion time. Different physicochemical methods were used to evaluate the Maillard reaction of dextrose with ACV to track the reaction in real infusion condition. Other large volume intravenous fluids were checked regarding the diluted drug stability profile. Differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and mass data proved the reaction of glucose with dextrose. A Maillard-specific high performance liquid chromatography (HPLC) method was used to track the reaction in real infusion condition in vitro. The nucleophilic reaction occurred in diluted parenteral preparations of acyclovir in 5% dextrose solutions. The best diluent solution was also selected as sodium chloride and introduced based on drug stability and also its adsorption onto different infusion sets (PVC or non PVC) to provide an acceptable administration protocol in clinical practices. Although, the Maillard reaction was proved and successfully tracked in diluted solutions, and the level of drug loss when diluted in dextrose was reported to be between 0.27 up to 1.03% of the initial content. There was no drug adsorption to common infusion sets. The best diluent for parenteral acyclovir is sodium chloride large volume intravenous fluid.

In situ observation of ninhydrin and phenylhydrazine reaction in solution by FTIR

The current work was performed for hydrazone formation reaction of ninhydrin with phenylhydrazine in chloroform by using "background defining method" in FTIR liquid cell. The method allowed following the consumption and formation of the reagent and product at the same time. Negative absorption bands are based on reagent consumption and positive absorbances are based on product formation. The method was applied for two different mol ratios (1:1, 1:3) of reagent. Both ratios resulted in same product (1,2,3-tris-phenylhydrazonoindan). The results showed that, phenylhydrazine react with all of the carbonyl groups in ninhydrin at both run.

Assessment of feasibility of maillard reaction between baclofen and lactose by liquid chromatography and tandem mass spectrometry, application to pre formulation studies

The aim of this study was to determine any possible, baclofen-lactose Maillard reaction products. Granules and tablets of baclofen and lactose were prepared and maintained in heat ovens for a certain time period. The effects of lactose type, addition of magnesium stearate, and water were monitored. Heated lactose and baclofen were analyzed using reverse-phase HPLC. Liquid chromatography tandem mass spectroscopy revealed nominal mass values consistent with baclofen-lactose, early-stage Maillard reaction condensation products (ESMRP). Multiple reaction monitoring confirmed the presence of ESMRP as well. FTIR analysis proved the formation of imine bond. The results indicated that baclofen undergoes a Maillard-type reaction with lactose.