p values and angles of phosphanes to predict their electronic and steric parameters.

Phosphanes play an important role in various applications, serving as a class of organic bases with basicities spanning more than 30 orders of magnitude. Accessing comprehensive basicity data for phosphanes has been challenging due to scattered information across multiple sources and notable gaps in the existing data. In this report, we present basicities (p values) of a diverse set of phosphanes, both newly measured or calculated and collected from the literature.

Coumarin-based derivatization reagent for LC-MS analysis of amino acids.

In this paper, we report about the application of a sensitive fluorescent derivatization reagent Coumarin151-N-Hydroxysuccinimidyl Carbamate (Cou151DSC) for amino compounds using high-performance liquid chromatography (HPLC) compatible with ultraviolet (UV), fluorescence detector (FLD) and electrospray ionization - tandem mass spectrometry (ESI-MS/MS)-positive mode. We optimized derivatization procedure and validated an analytical method to determine 24 amino acids in Kvass drink using Norvaline as an internal standard. Compared to 6-Aminoquinolyl-N-Hydroxysuccinimidyl Carbamate (6-AQC), the derivatization with Cou151 DSC is faster and milder, for 5 min at 40°C instead of 15 min at 55°C.

Comparison of two azobenzene-based amino acid derivatization reagents for LC-MS/MS analysis in positive and negative ESI modes.

Derivatization reagents based on azobenzene containing different N-hydroxysuccinimidyl moieties- AzoB (carbamate) and AzoC (ester) - are proposed for the LC-ESI-MS analysis of free amino acids in fermented beverages and juices. A dual comparison between LC-MS/MS in positive and negative ESI modes in dynamic Multiple Reaction Monitoring (dMRM) and Neutral Loss Scan was investigated. The results indicate that the studied carbamate derivatization reagent, AzoB, can be employed for targeted analysis (MS/MS) but also for non-targeted analysis of derivatized amino acids thanks to its constant neutral loss (223 Da) that is the same in both ionisation modes.

Quantifying Acidity in Heterogeneous Systems: Biphasic p Values.

Acidities of lipophilic compounds, such as various ligands or catalysts, in systems consisting of an aqueous phase at equilibrium with a water-immiscible phase (lipid bilayers, phase transfer catalysis, sensor membranes, to name just few) are typically approximated by the aqueous p values. Our research shows that such approximations can lead to seriously biased estimations of the acidities as the bulk of solvated H ions reside in the aqueous phase, while the lipophilic species─both neutral acid and anion─predominantly reside in the organic phase. Therefore, the use of aqueous p in such situations is not justified.

Novel Lipophilic Fluorophores with Highly Acidity-Dependent Two-Photon Response.

Lipophilic fluorophores are widely implemented in nonlinear microscopy; however, few existing membrane-specific probes combine the high brightness of two-photon excited fluorescence (2PEF) with pH sensitivity. Herein we describe four novel two-photon excited fluorophores, based on a coumarin 151 core structure, where lipophilicity is induced by a covalently attached phosphazene moiety. Changing the environmental acidity using trifluoromethanesulfonic (triflic) acid leads to profound changes in the linear fluorescence and 2PEF characteristics, due to chromophores' switching between neutral- and protonated forms.

Quantitative electrospray ionization efficiency scale: 10 years after.

Rationale: The first comprehensive quantitative scale of the efficiency of electrospray ionization (ESI) in the positive mode by monoprotonation, containing 62 compounds, was published in 2010. Several trends were found between the compound structure and ionization efficiency (IE) but, possibly because of the limited diversity of the compounds, some questions remained. This work undertakes to align the new data with the originally published IE scale and carry out statistical analysis of the resulting more extensive and diverse data set to derive more grounded relationships and offer a possibility of predicting logIE values.

Experimental and Computational Study of Aminoacridines as MALDI(-)-MS Matrix Materials for the Analysis of Complex Samples.

Monoaminoacridines (1-, 2-, 3-, 4-, and 9-aminoacridine) were studied for suitability as matrices in the negative ion mode matrix-assisted laser desorption/ionization mass spectrometry (MALDI(-)-MS) analysis of various samples. This is the first study to examine 1-, 2-, and 4-aminoacridine as potential matrix material candidates for MALDI(-)-MS. In addition, spectral (UV-Vis absorption and fluorescence), proton transfer-related (basicity and autoprotolysis), and crystallization properties of these compounds were characterized experimentally and/or computationally.