Metabolomic profiling of virulent and non-virulent Beauveria bassiana strains: insights into the pathogenicity of Tetranychus truncatus.

In this study, the pathogenicity of local Beauveria bassiana strains was elucidated using molecular and metabolomics methodologies. Molecular verification of the B. bassiana-specific chitinase gene was achieved via phylogenetic analysis of the Bbchit1 region. Subsequent metabolomic analyses employing UPLC-Q-TOF-MS revealed a different number of non-volatile metabolite profiles among the six B. bassiana strains. Bb6 produced the most non-volatile compounds (17) out of a total of 18, followed by Bb15 (16) and Bb12 (15). Similarly, Bb5, Bb8, and Bb21, three non-virulent B. bassiana strains, produced 13, 14, and 14 metabolites, respectively. But unique secondary metabolites like bassianolide and beauvericin, pivotal for virulence and mite management, were exclusively found in the virulent strains (Bb6, Bb12, and Bb15) of B. bassiana. The distinctive non-volatile metabolomic profiles of these strains underscore their pathogenicity against Tetranychus truncatus, suggesting their promise in bio-control applications.

Pitfalls in the Optimization of Conformer Populations to Maximize the Similarity between Predicted and Experimental Chiroptical Spectra.

The conformational populations of pantolactone, epichlorohydrin, and N-acetyl-tryptophan methyl ester were investigated by using similarity analysis between their calculated and experimental chiroptical spectra. By performing the analysis on pantolactone using two different chiroptical methods, namely, vibrational circular dichroism and Raman optical activity, it was found that the optimal sets of conformers do not match between the two methods, indicating that the conformational populations obtained by optimizing the similarity between calculated and experimental spectra are unlikely to be more accurate than energy-based Boltzmann populations. Also, it was found for pantolactone, epichlorohydrin, and N-acetyl-tryptophan methyl ester that the similarity between calculated and experimental spectra would often not vary significantly if each of the populated conformers was discarded, one at a time. This observation indicates that more than one set of conformers can provide acceptable similarity between the predicted and experimental spectra. Therefore, the correct set of conformers cannot be accurately determined by similarity analysis.

Influence of microsolvation on vibrational circular dichroism spectra in dimethyl sulfoxide solvent: A Bottom-Up approach using Quantum cluster growth.

Chiroptical spectroscopic measurements serve as routine methods to assign the absolute configuration of chiral compounds and interpret their conformational behavior in solution. One common challenge is the use of strongly hydrogen-bonding solvents, which can significantly bias the conformational ensemble and affect the vibrational circular dichroism (VCD) active bands in solution. One such solvent is dimethyl sulfoxide (DMSO)-an excellent solvent for stubborn compounds-that must be explicitly considered in VCD analysis. Explicit consideration of solvent remains a critical challenge in chiroptical spectroscopy due to the need to explore solute-solvent conformational space and the computational expense in modeling these clusters. Interested in the recent development of the Quantum Cluster Growth (QCG) program by the Grimme lab, we set out to model and interpret previously reported VCD spectra for several molecules using their efficient program. Our purposes are two-fold: (1) to investigate the applicability of the QCG program to the problem of reproducing VCD spectra in DMSO solvent and (2) to identify limitations in using this approach. We find that we can conveniently model and analyze the VCD spectra of investigated molecules in DMSO. However, the final set of conformers used for VCD calculations are functional dependent and different sets of conformers can provide satisfactory quantitative agreement between experimental and predicted VCD spectra. We hope that this study provides guidance for future chiroptical studies in the challenging DMSO solvent.

Chiral explosives: A theoretical investigation of structure and chiroptical properties of triacetone triperoxide and hexamethylene triperoxide diamine.

Triacetone triperoxide (TATP) and hexamethylene triperoxide diamine (HMTD) are cyclic peroxides that exhibit atropisomerism resulting from restricted rotation around three peroxide bonds. As a result, one pair of enantiomers with D3 symmetry and another pair of enantiomers with C2 symmetry can be identified. Previous studies, based on mass spectrometry data and computational results, have shown that conformations of TATP with D3 and C2 symmetry can be isolated. Assuming that enantiomer samples of TATP and HMTD can be obtained with sufficient enantiopurity, we investigated their chiroptical properties, namely, optical rotatory dispersion (ORD), vibrational circular dichroism (VCD), and Raman optical activity (VROA). ORD curves and VCD spectra are seen to be very similar for D3 - and C2 -symmetric atropisomers with the same overall helicity. Predicted VROA results, however, show significant differences between D3 - and C2 -symmetric atropisomers with the same overall helicity. The D3 -symmetric atropisomer is predicted to exhibit considerably larger magnitude vibrational optical activity signals than the C2 -symmetric atropisomer.

Synthesis, characterization and absolute configurations of methyl ladderanoates.

Methyl esters of [5]-ladderanoic acid and [3]-ladderanoic acid were prepared by esterification of the acids isolated from biomass at a wastewater treatment plant. Optical rotations at six different wavelengths (633, 589, 546, 436, 405 and 365 nm) and vibrational circular dichroism (VCD) spectra in the 1800-900 cm-1 region were measured in CDCl3 solvent and compared with quantum chemical (QC) predictions using B3LYP functional and 6-311++G(2d,2p) basis set with polarizing continuum model representing the solvent. QC predictions gave negative optical rotations at all six wavelengths for (R)-methyl [5]-ladderanoate and positive optical rotations for (R)-methyl [3]-ladderanoate, the same signs as previously reported for the corresponding acids. The crystal structure of (-)-methyl [5]-ladderanoate independently confirmed (R) configuration. The QC-predicted VCD spectra using Boltzmann population weighted spectra of individual conformers did not provide satisfactory quantitative agreement with the experimental VCD spectra. An improved quantitative agreement for VCD spectra could be obtained when conformer populations were optimized to maximize the similarity between experimental and predicted VCD spectra, but more improvements in VCD predictions are needed.

"Metabolomic diversity of local strains of Beauveria bassiana (Balsamo) Vuillemin and their efficacy against the cassava mite, Tetranychus truncatus Ehara (Acari: Tetranychidae)".

A desirable substitute for chemical pesticides is mycopesticides. In the current investigation, rDNA-ITS (Internal transcribed spacer) and TEF (Transcriptional Elongation Factor) sequencing were used for molecular identification of six Beauveria bassiana strains. Both, leaf discs and potted plant bioassaye were carried out to study their pathogenicity against the cassava mite, Tetranychus truncatus. LC50 and LC90 values of potential B. bassiana strains were estimated. We also discovered a correlation between intraspecific B. bassiana strains pathogenicity and comprehensive metabolome profiles. Bb5, Bb6, Bb8, Bb12, Bb15, and Bb21 strains were identified as B. bassiana by sequencing of rDNA-ITS and TEF segments and sequence comparison to NCBI (National Center for Biotechnology Information) GenBank. Out of the six strains tested for pathogenicity, Bb6, Bb12, and Bb15 strains outperformed against T. truncatus with LC50 values 1.4×106, 1.7×106, and 1.4×106 and with a LC90 values 7.3×107, 1.4×108, and 4.2×108 conidia/ml, respectively, at 3 days after inoculation and were considered as potential strains for effective mite control. Later, Gas Chromatography-Mass Spectrometry (GC-MS) analysis of the above six B. bassiana strains was done on secondary metabolites extracted with ethyl acetate revealed that the potential B. bassiana strains (Bb6, Bb12, and Bb15) have higher levels of acaricidal such as Bis(dimethylethyl)-phenol: Bb6 (5.79%), Bb12 (6.15%), and Bb15 (4.69%). Besides, insecticidal (n-Hexadecanoic acid), and insect innate immunity overcoming compound (Nonadecene) were also identified; therefore, the synergistic effect of these compounds might lead toa higher pathogenicity of B. bassiana against T. truncatus. Further, these compounds also exhibited two clusters, which separate the potential and non-potential strains in the dendrogram of Thin Layer Chromatography. These results clearly demonstrated the potentiality of the B. bassiana strains against T. truncatus due to the occurrence of their bioactive volatile metabolome.

"Multilocus sequence analysis for population diversity of indigenous entomopathogenic fungus Beauveria bassiana and its bio-efficacy against the cassava mite, Tetranychus truncatus Ehara (Acari: Tetranychidae)".

Beauveria bassiana is an entomopathogenic fungus that causes the white muscadine disease in insects. The majority of entomopathogenic fungi are soil and insect borne, 15 soil samples were collected from seven different locations during 2021, from January to December. Similarly, during 2022, March to December, 15 fungus-infected insect specimens were collected from five different locations hence soil and insect samples from various ecosystems were collected. As a result, 30 B. bassiana isolates from 11 different geographical areas were identified using morphological characteristics and multilocus sequence data in this investigation. The taxonomical positions of the isolates were determined using morphological characteristics and phylogenetic inferences based on three loci (Internal Transcribed Sequence, Elongation Factor-1α, and B. bassiana chitinase 1). In phylogenetic analysis of B. bassiana, the Maximum Likelihood analytical method produced distinct tree topology when compared to Neighbor-joining and minimum evolution. Three isolates viz., Bb3, Bb7 and Bb20 were found closely linked with reference isolate (KTU-24) and other showed the higher population diversity among them. The genetic distances of 30 B. bassiana isolates revealed that 15 were not closely related (D varied from 0.003 to 0.036). The pathogenicity of B. bassiana isolates from various hosts along with one commercial formulation (Beveroz) was assessed against Tetranychus truncatus under in vitro conditions by a completely randomized design (CRD) experiment. The same experiment was repeated thrice to confirm the pathogenicity of B. bassiana against T. truncatus. Later, the collected T. truncatus mortality data was converted into corrected mortality by using the Abbott formula and the values were examined using analysis of variance (ANOVA) in SPSS 23.0 software. Duncan's Multiple Comparison Test was also done to compare the percentage mortality rates among the 30 B. bassiana isolates. The recorded results showed that the Bb6, Bb15 and Bb12 isolates caused significantly higher mortality of T. truncatus, i.e., 97.73, 96.73 and 94.50% respectively, than the other isolates. This study showed the relativeness among the B. bassiana isolates and establishes their bio-efficacy against T. truncatus, which further can be used for commercialization as bio-pesticide.

Chiroptical spectroscopic studies for the absolute configuration determination of hexahydrocurcumin and octahydrocurcumin.

Hexahydrocurcumin (HHC) and octahydrocurcumin (OHC) were synthesized, and their enantiomers were separated using supercritical fluid chromatography. The absolute configurations (ACs) of HHC and OHC were independently determined using experimental measurements and quantum theoretical predictions of vibrational circular dichroism, electronic circular dichroism, and optical rotatory dispersion. These studies lead to AC assignments of (-)-(R)-HHC and (+)-(R,R)-OHC. The AC of OHC is further confirmed by its structure determined from single crystal x-ray diffraction.

A prospective study to evaluate febrile neutropenia incidence in patients receiving pegfilgrastim on-body injector vs other choices.

PURPOSE: We evaluated the incidence of febrile neutropenia (FN) and related clinical outcomes among patients treated with myelosuppressive chemotherapy for nonmyeloid malignancies who received pegfilgrastim on-body injector (OBI) or other options (Other) for FN prophylaxis. METHODS: In this prospective observational study, adult patients with breast, prostate, or lung cancer, or non-Hodgkin lymphoma at risk for FN were stratified into subgroups based on FN prophylaxis used in the first chemotherapy cycle: pegfilgrastim OBI vs Other (pegfilgrastim or biosimilar pegfilgrastim prefilled syringe, daily filgrastim, or no granulocyte colony-stimulating factor [G-CSF]) for up to 4 planned chemotherapy cycles. RESULTS: This US study enrolled 2575 eligible patients (OBI, 1624; Other, 951). FN incidence was lower in the OBI group (6.4% [95% CI, 5.2-7.6%]) than in the Other group (9.4% [7.5-11.2%]), with a relative risk (RR) of 0.66 (0.47-0.91; p = .006). A decreased risk of dose delays among patients receiving pegfilgrastim OBI vs Other was observed (RR for ≥ 5 days: 0.64 [0.42-0.96], p = .023; RR for ≥ 7 days: 0.62 [0.40-0.91], p = .016). Adherence, defined as G-CSF support for all chemotherapy cycles, was 94.0% (92.9-95.2%) in the OBI group compared with 58.4% (55.2-61.5%) in the Other group. Compliance with pegfilgrastim, defined as administration the day after chemotherapy, was 88.3% in the OBI group and 48.8% in the prefilled syringe group. CONCLUSION: Patients receiving pegfilgrastim OBI had a lower incidence of FN compared with those receiving alternatives. The OBI was associated with improved adherence to and compliance with clinically recommended G-CSF prophylaxis.

A prospective cohort study to evaluate the incidence of febrile neutropenia in patients receiving pegfilgrastim on-body injector versus other options for prophylaxis of febrile neutropenia: breast cancer subgroup analysis.

BACKGROUND: Breast cancer chemotherapy often carries a high risk of febrile neutropenia (FN); guidelines recommend prophylaxis with granulocyte colony-stimulating factor (G-CSF), such as pegfilgrastim. Neulasta® Onpro® on-body injector (OBI) is a delivery device administering pegfilgrastim approximately 27 h after application. METHODS: This prospective study examined patients with breast cancer who received chemotherapy with a high risk of FN, receiving OBI ("OBI") or other options (other G-CSF or none; "other"). The primary endpoint was FN incidence; secondary endpoints included chemotherapy delivery, adherence (G-CSF in all cycles), compliance (G-CSF day after chemotherapy), and FN incidence in patients receiving curative or palliative treatment. RESULTS: A total of 1776 patients with breast cancer were enrolled (OBI, n = 1196; other, n = 580). Across all cycles, FN incidence was lower for OBI (4.4% [95% CI, 3.3-5.6%]) than other (7.4% [5.3-9.6%]). For curative treatment, the FN incidence across all cycles was lower for OBI (4.6% [3.4-5.8%]) than for other (7.1% [5.0-9.3%]). For palliative treatment (OBI, n = 33; other, n = 20), 3 patients (15%) in the other and none in the OBI group had FN. After adjusting for baseline covariates, FN incidence remained lower for OBI (4.6% [3.5-6.1%]) versus other (7.8% [5.7-10.5%]). Adherence was higher for OBI (93.8%) than for other G-CSF (69.8%), as was compliance (90.5 and 53.2%, respectively). Chemotherapy dose delays/reductions were similar for OBI (4.7%/32.3%, respectively) and other (4.7%/30.0%) groups. CONCLUSION: Pegfilgrastim OBI was associated with a lower FN incidence in patients with breast cancer compared to other options for FN prophylaxis. TRIAL REGISTRATION: www. CLINICALTRIALS: gov , NCT02178475, registered 30 June, 2014.

Absolute configuration of a [1]rotaxane determined from vibrational and electronic circular dichroism spectra.

The experimental vibrational circular dichroism (VCD) and electronic circular dichroism (ECD) spectra were measured for the enantiomers of [1]rotaxane 1. These experimental spectra have been analyzed using predicted VCD and ECD spectra for (S, Rmp ) or (S, Smp ) diastereomers using density functional theory. This comparison allowed for a definitive assignment of the absolute configuration of 1.

Chiral Molecular Structure Determination for a Desired Compound Just from Its Molecular Formula and Vibrational Optical Activity Spectra.

A novel proof-of-concept model for chiral molecular structure determination using just the molecular formula and vibrational optical activity (VOA) spectra is presented. To verify this concept, the molecular formula of a desired compound is used to generate all possible chiral structural isomers and their VOA spectra are predicted. The similarity analyses of predicted VOA spectra were then carried out in two different ways: (a) similarity between VOA spectrum of one structural isomer with those of the rest, referred to as cross-correlations; (b) similarity between VOA spectra of all chiral structural isomers with the experimental VOA spectra of the desired compound. Three different molecular formulae, C4H8O, C3H5ClO, and C6H10O, and their chiral structural isomers (6, 9, and 75 respectively), were investigated. In each case, the correct chiral molecular structure of the desired compound was identified without ambiguity. Cross-correlation analysis revealed the uniqueness of VOA spectra in deducing the chiral molecular structure solely from its molecular formula. Different chiral structural isomers associated with the molecular formula CH3NO2 were also found to have no significant cross-correlations between their VOA spectra, opening a pathway to detect and identify the elusive chiral N-hydroxyoxaziridine from its VOA spectra.

Prophylactic pegfilgrastim to prevent febrile neutropenia among patients receiving biweekly (Q2W) chemotherapy regimens: a systematic review of efficacy, effectiveness and safety.

BACKGROUND: Pegfilgrastim, a long-acting granulocyte colony-stimulating factor (G-CSF), is commonly used to prevent febrile neutropenia (FN), a potentially life-threatening complication, following myelosuppressive chemotherapy. The FDA label for pegfilgrastim specifies that it should not be administered 14 days before or within 24 h of administration of myelosuppressive chemotherapy, precluding the use of pegfilgrastim in biweekly (Q2W) regimens. The National Comprehensive Cancer Network and the European Organisation for Research and Treatment of Cancer guidelines support the use of prophylactic pegfilgrastim in patients receiving Q2W regimens. The objective of this study was to systematically review evidence from randomized clinical trials (RCTs) and observational studies that describe the effectiveness and safety of prophylactic pegfilgrastim in preventing FN among patients receiving Q2W regimens. METHODS: An Ovid MEDLINE, Embase, and Cochrane Library literature search was conducted to evaluate the evidence regarding efficacy, effectiveness, and safety of prophylactic pegfilgrastim versus no prophylactic pegfilgrastim or prophylaxis with other G-CSF in patients who were receiving Q2W chemotherapy regimens with high (> 20%) or intermediate (10-20%) risk of FN for a non-myeloid malignancy. Studies that addressed absolute or relative risk of FN, grade 1-4 neutropenia, all-cause or any hospitalization, dose delays or dose reductions, adverse events, or mortality were included. Studies where the comparator was a Q3W chemotherapy regimen with primary prophylactic pegfilgrastim were also included. RESULTS: The initial literature search identified 2258 publications. Thirteen publications met the eligibility criteria, including eight retrospective, one prospective, one phase 1 dose escalation study, and three RCTs. In nine of the 13 studies reporting incidence of FN, and in seven of the nine studies reporting incidence of neutropenia, administration of prophylactic pegfilgrastim in patients receiving Q2W regimens resulted in decreased or comparable rates of FN or neutropenia compared with patients receiving filgrastim, no G-CSF, lipefilgrastim or pegfilgrastim in Q3W regimens. In six of the nine studies reporting safety data, lower or comparable safety profiles were observed between pegfilgrastim and comparators. CONCLUSIONS: In a variety of non-myeloid malignancies, administration of prophylactic pegfilgrastim was efficacious in reducing the risk of FN in patients receiving high- or intermediate-risk Q2W regimens, with an acceptable safety profile. TRIAL REGISTRATION: PROSPERO registration no: CRD42019155572 .

Rice leaf diseases prediction using deep neural networks with transfer learning.

Rice (Oryza sativa) is a principal cereal crop in the world. It is consumed by greater than half of the world's population as a staple food for energy source. The yield production quantity and quality of the rice grain is affecting by abiotic and biotic factors such as precipitation, soil fertility, temperature, pests, bacteria, virus, etc. For disease management, farmers spending lot of time and resources and they detect the diseases through their penniless naked eye approach which leads to unhealthy farming. The advancement of technical support in agriculture greatly assists for automatic identification of infectious organisms in the rice plants leaves. The convolutional neural network algorithm (CNN) is one of the algorithms in deep learning has been triumphantly invoked for solving computer vision problems like image classification, object segmentation, image analysis, etc. In our work, InceptionResNetV2 is a type of CNN model utilized with transfer learning approach for recognizing diseases in rice leaf images. The parameters of the proposed model is optimized for the classification task and obtained a good accuracy of 95.67%.

Absolute configuration of seco-eudesmanolide inuloxin D from experimental and predicted chiroptical studies of its 4-O-acetyl derivative.

Sesquitepenoids inuloxins A-D, belonging to different subgroups, were isolated from Dittrichia viscosa and showed potential biocontrol of some parasitic plants as Pelipanche, Orobanche, and Cuscuta species. The absolute configurations of the first three inuloxins A-C were previously determined by using experimental and computational chiroptical spectroscopic methods. The absolute configuration of inuloxin D remains to be established. The bioactive inuloxin E, closely related to inuloxin D, was recently isolated from the same plant organic extract. The same relative configuration of inuloxin D was assigned to inuloxin E by comparison of their NMR spectroscopic data. The absolute configurations of inuloxin D and inuloxin E are suggested in this work by analysis of the experimental and predicted chiroptical properties of the 4-O-acetyl derivative of inuloxin D.

Trends in use of primary prophylactic colony stimulating factors and neutropenia-related hospitalization in commercially insured patients receiving myelosuppressive chemotherapy in the United States: 2005-2017.

PURPOSE: Describe temporal changes in use of myelosuppressive chemotherapy, primary prophylactic colony-stimulating factor, and neutropenia-related hospitalization, in commercially insured patients. METHODS: Using a large commercial administrative database, we identified annual cohorts of adult patients diagnosed with breast or lung cancer, or non-Hodgkin lymphoma and initiating myelosuppressive chemotherapy during 2005-2017. We described yearly changes in proportions of myelosuppressive chemotherapy by febrile neutropenia risk category (high, intermediate, unclassified) and proportion of prophylactic colony-stimulating factor use and unadjusted incidence of neutropenia-related hospitalization in the first cycle of myelosuppressive chemotherapy. RESULTS: Annual cohorts included 4383-5888 eligible patients during 2005-2017. The proportion of eligible patients aged ≥ 65 years increased from 26.0% in 2005 to 58.2% in 2017. Myelosuppressive chemotherapy use with regimens with high risk for febrile neutropenia increased from 15.1% in 2005 to 31.0% in 2017; and regimens with intermediate risk for febrile neutropenia decreased from 63.7% to 48.1% in 2017. Prophylactic colony-stimulating factor use increased from 41.6% in 2005 to 54.3% in 2017. Crude incidence of neutropenia-related hospitalization for all cancers increased from 2.0% to 3.1%, with a substantial increase in neutropenia-related hospitalization observed among non-Hodgkin lymphoma patients (2.8% to 8.5%) during 2005-2017. CONCLUSION: Among adult patients with breast and lung cancer, and non-Hodgkin lymphoma receiving myelosuppressive chemotherapy, use of regimens with high risk for febrile neutropenia increased, as did the use of prophylactic colony-stimulating factors after 2005. Incidence of neutropenia-related hospitalization increased slightly, particularly among non-Hodgkin lymphoma patients. Further studies are required to understand this increasing trend of neutropenia-related hospitalization, changing patient-level risk factors, and febrile neutropenia management.

How important are the intermolecular hydrogen bonding interactions in methanol solvent for interpreting the chiroptical properties?

Two crispine A analogs and tetrahydrofuro[2,3-b]furan-3,3a(6aH)-diol, endowed with hydroxyl groups that can participate in intramolecular hydrogen bonding, have been synthesized and experimental vibrational circular dichroism (VCD) spectra and optical rotatory dispersion (ORD) data have been measured in CD3OD/CH3OH solvents. The absolute configurations (ACs) of these compounds have been determined using their synthetic schemes, supplemented wherever possible with X-ray diffraction data. The ACs are also analyzed with quantum chemical (QC) calculations of VCD and ORD utilizing implicit solvation as well as explicit solvation models, with the later employing classical molecular dynamics (MD) simulations. It is found that VCD calculations with implicit solvation model are adequate for determining the ACs, despite propensity of studied compounds for intermolecular hydrogen bonding between solute and solvent molecules. This observation is important because time-consuming MD simulations may not be necessary in the type of situations studied here. Additionally, it is found that the QC predicted VCD spectra provided enough diastereomer discrimination for determining the correct AC of studied compounds independently. The same observation did not apply to ORD.

Impact of arsenic-polluted groundwater on soil and produce quality: a food chain study.

The experiment was conducted to assess the impact of arsenic (As)-contaminated groundwater irrigation on soil health and crop quality. Geo-referenced groundwater, soil, and crop produce samples were collected from the middle Gangetic plains of Maner block of Patna and were analyzed for As content. The result showed that long-term application of As-contaminated groundwater (0.017 to 0.677 mg L-1) buildup significant amount of As in the soil (0.41 to 8.66 mg kg-1). A significant correlation (r2 = 0.922) was also observed between As content in groundwater and the soil. The content of As in groundwater also affected crop quality and accumulated metal content in different crop parts. Total As content in crop samples ranged from 0.010 to 0.963 µg g-1 of dry weight. The average As content in crop followed order: oilseeds > cereals > vegetables > pulses. Therefore, produce quality should be monitored frequently for As uptake as there is a great chance of As accumulation in food crops. Hence, these approaches are useful for the formulation of policy guidelines for the management of As-containing groundwater and routine risk assessment of As-contaminated soils.

Chemical Synthesis of [2H]-Ethyl Tosylate and Exploration of Its Crypto-optically Active Character Combining Complementary Spectroscopic Tools.

Small chiral molecules are excellent candidates to push the boundaries of enantiodiscrimination analytical techniques. Here is reported the synthesis of two new deuterated chiral probes, (R)- and (S)-[2H]-ethyl tosylate, obtained with high enantiomeric excesses. Due to their crypto-optically active properties, the discrimination of each enantiomer is challenging. Whereas their enantiopurity is determined by 2H NMR in chiral anisotropic media, their identification was performed by combining quantum chemical calculations and vibrational circular dichroism analysis.

Optical purity, enantiomeric excess and the Horeau effect.

The optical purity of an enantiomeric mixture deduced from specific rotation measurements was found by Horeau to be different from its enantiomeric excess, which came to be known as the Horeau effect. This observation had important implications in the practical use of specific rotations and has led to investigations on homochiral and heterochiral aggregation processes. In this review, dedicated to the Horeau principle, the theoretical basis for the observance of the Horeau effect and a survey of the specific rotation studies investigating the Horeau effect are provided, and possible future investigations are suggested.