Homologous Series Of Compounds Research Articles

Studies of temperature dependent Raman spectroscopy of two nematic liquid crystalline compounds of homologous series

Raman spectroscopy is an important tool to understand the structural and molecular behaviour of the liquid crystals when they undergo through different temperatures. It also helps to understand the different phase changes of the liquid crystal material as temperature changes. In this work, the structural properties of two nematic liquid crystals having relatively high clearing temperature namely 4 butylcyclohexyl-3, 5-difluoro-4- isothiocyanato biphenyl and 4-pentylcyclohexyl-3, 5-difluoro-4-isothiocyanato biphenyl are studied. The study is done using temperature dependent Raman spectroscopy. From the studies of the two compounds it has been found that the experimental values are agree well with the various functional groups and different bond assignments recorded in literature. This agreement validates the presence of different functional groups and different stretching bonds in the two studied liquid crystal compounds. Deformations of some of the peak positions of the two liquid crystal compounds have been observed with the change in phase at different temperature. Also to understand the behaviour of the Raman peak near the clearing temperatures of the liquid crystal compounds the linewidth of the different peak values at different temperature have also been studied. From the line width study, the various phase transition temperatures of the two liquid crystalline compounds can be confirmed.

Leaning induced layer undulated tilted smectic phase of asymmetric bent-core liquid crystals.

We report the synthesis and experimental studies on the liquid crystalline phase of a homologous series of compounds comprised of strongly asymmetric bent-core banana shaped molecules. Our x-ray diffraction studies clearly indicate that the compounds exhibit a frustrated tilted smectic phase with layer undulated structure. The low value of the dielectric constant as well as switching current measurements indicate the absence of polarization in this layer undulated phase. In spite of the absence of polarization, a planar aligned sample can be transformed irreversibly to a higher birefringent texture on the application of a high electric field. The zero field texture can only be retrieved by heating the sample to the isotropic phase and cooling it subsequently to the mesophase. We propose a double tilted smectic structure having layer undulation to account for the experimental observations with the layer undulation arising due to the leaning of the molecules in the layer.

Characterization of Corn Silk Extract Using HPLC/HRMS/MS Analyses and Bioinformatic Data Processing.

In addition to having different biological activities of interest, corn silks play a role in the defense of plants. While benzoxamines and flavonoids have already been identified as molecules of plant defense and growth mechanisms, knowledge on the phytochemical composition of corn silk is lacking. Such knowledge would make it possible to better select the most effective varieties to improve resistance or bioactive properties. In this article, an approach was implemented to map a corn silk extract in two complementary ways. The first one involved working with UHPLC/HRMS data and Kendrick and van Krevelen plots to highlight a homologous series of compounds, such as lipids from 17 to 23 carbons, monoglycosylated flavonoids from 21 to 24 carbons, diglycosylated flavonoids of 26 to 28 carbons and organic acids of 14 to 19 carbons. The second way was to analyze the sample in UHPLC/HRMS2 and to plot mass spectral similarity networks with the GNPS platform and Cytoscape software to refine identification. By combining the information obtained, we were able to propose an identification for 104 detected molecules, including 7 nitrogenous, 28 lipidic and 67 phenolic compounds, leading to the first detailed phytochemical analysis of corn silk extract.

Soluble Sulfur-Bearing Organic Compounds in Carbonaceous Meteorites: Implications for Chemical Evolution in Primitive Asteroids

Sulfur comprises various compound forms in natural environments and could have played important roles in chemical evolution in the universe. Various soluble organosulfur compounds and inorganic sulfur oxides were identified in the methanol extracts of three carbonaceous chondrites (Murchison, Tagish Lake, and Allende) using high-performance liquid chromatography coupled with high-resolution mass spectrometry. The most abundant S-bearing organic compound was hydroxymethane sulfonic acid (HMSA, HOCH2SO3H), which is reported from a meteorite for the first time, at a concentration of 201 nmol/g in the Murchison meteorite. Because HMSA is known to be produced by the reaction of formaldehyde (HCHO) and bisulfite (HSO3–), this result indicates that formaldehyde should be abundant prior to the reaction with HSO3– in the meteorite parent bodies. The bisulfite derivatives of glycolaldehyde and glyceraldehyde were further identified in the methanol extract, suggesting that the formose reaction had proceeded during the aqueous alteration. The finding of these sugar–HSO3– adducts suggests that the formose reaction might have been controlled by the presence of sulfur species in the body. Furthermore, alkylated sulfonic acids (CnH2n+1SO3H) were also present as a series of homologous compounds up to C14 in the Murchison meteorite, even though previous studies found only C1–C4 sulfonic acids. In addition to organosulfur compounds, variable inorganic polysulfur oxides and acids were detected. The abundant S-bearing compounds in the meteorites imply important roles of sulfur in the organic reactions in carbonaceous asteroids.

Fast Prediction of the Equivalent Alkane Carbon Number Using Graph Machines and Neural Networks.

The hydrophobicity of oils is a key parameter to design surfactant/oil/water (SOW) macro-, micro-, or nano-dispersed systems with the desired features. This essential physicochemical characteristic is quantitatively expressed by the equivalent alkane carbon number (EACN) whose experimental determination is tedious since it requires knowledge of the phase behavior of the SOW systems at different temperatures and for different surfactant concentrations. In this work, two mathematical models are proposed for the rapid prediction of the EACN of oils. They have been designed using artificial intelligence (machine-learning) methods, namely, neural networks (NN) and graph machines (GM). While the GM model is implemented from the SMILES codes of a 111-molecule training set of known EACN values, the NN model is fed with some σ-moment descriptors computed with the COSMOtherm software for the 111-molecule set. In a preliminary step, the leave-one-out algorithm is used to select, given the available data, the appropriate complexity of the two models. A comparison of the EACNs of liquids of a fresh set of 10 complex cosmetic and perfumery molecules shows that the two approaches provide comparable results in terms of accuracy and reliability. Finally, the NN and GM models are applied to nine series of homologous compounds, for which the GM model results are in better agreement with the experimental EACN trends than the NN model predictions. The results obtained by the GMs and by the NN based on σ-moments can be duplicated with the demonstration tool available for download as detailed in the Supporting Information.

Expanding multiple anion superlattice chemistry: Synthesis, structure and properties of Bi4O4SeBr2 and Bi6O6Se2Cl2

The synthesis, structure, and properties of the three-anion superlattice materials Bi4O4SeBr2 and Bi6O6Se2Cl2 are reported. These materials crystallise in structures that form part of a homologous series of compounds comprised of stackings of BiOCl- and Bi2O2Se-like units. Bi4O4SeBr2 is analogous to Bi4O4Se2Cl2, whereas Bi6O6Se2Cl2 contains an additional Bi2O2Se layer that produces off-centred anions. The band gaps of both materials are indirect, with Eg ​= ​1.15(5) eV, and the materials behave as doped semiconductors with very low thermal conductivities. These materials expand the synthetic scope of multiple anion superlattice materials and, with optimisation, may also be platforms for future thermoelectric materials.

Structural analysis of bis(pyridyl)diimines: Factors affecting the molecular geometry and supramolecular packing

Systematic analysis of structural features of a series of bis(pyridyl)diimines is done to have an understanding on the effect of different types of interactions in modulating the molecular geometry and final packing of the molecules in the solid state. Supramolecular synthons that may result from weak interactions such as CH···N and aromatic interactions are difficult to predict and hence analyzing homologous series of compounds, which can organize only by weak interactions will lead to generating data sets on various possibilities of synthons. In the series of bis(pyridyl)diimines, small variation in the molecular features such as position of nitrogen on pyridyl ring, presence of hydrogen or methyl group on imine carbon and changing the alkyl spacer length is being related to the observed changes in the occurrence of non-covalent interactions and finally in the crystal packing in the solid state. Cooperative effect of intermolecular interactions and steric factors decide the final structural arrangement, which is being inferred by observing the solid state arrangement of the compounds. Crystallization induced emission of the bis(pyridyl)diimines is also studied and correlated with their structural features and the overall supramolecular architecture.

Analysis of volatile oxidized oligomers from polyolefins by off-line normal phase high performance liquid chromatography and one-dimensional and comprehensive two-dimensional gas chromatography

The off-line coupled high performance liquid chromatography - gas chromatography - mass spectrometry (HPLC-GC–MS) was used for the analysis of oxidized oligomers from polyolefins. In order to optimize the HPLC fractionation method, a complex substance mixture of volatile organic compounds (VOC) from the provoked thermal oxidation of polyethylene (PE) was investigated. The fractionation was performed by normal phase HPLC, which separated the analytes according to their polarity. The seven obtained fractions were transferred off-line to the GC–MS. By means of fractionation nearly all coelutions present in the total extract could be avoided, which facilitated the identification of substances considerably. In addition, a separation according to functional moieties of substances was achieved, resulting in homologous series of compounds in the individual fractions: polyolefin oligomeric hydrocarbons (POH) in fraction 1, aldehydes and 7-, 6-, and 5-ketones in fraction 3, 2-ketones and alkenals in fraction 4, lactones and carboxylic acids in fraction 5, 1- and 2-alcohols in fraction 6 and diones in fraction 7, respectively. In this work, 7-, 6- and 5-ketones, δ-lactones, 2-alcohols and diones were identified for the first time in oxidized PE. Verification of fractionation and substance identification was done by comprehensive two-dimensional gas chromatography - time of flight - mass spectrometry (GCxGC-TOF-MS) measurements as well as off-line HPLC-GC–MS measurements using a mixture of reference substances. The fractionation approach was applied for the analysis of a commercial PE film after melt flow extrusion. POH were eluted in fraction 1, while n-aldehydes (with a carbon chain length of C11-18) were identified in fraction 3 and 2-ketones (C13-15) in fraction 4. The amounts of the individual detectable oxidized oligomers were estimated semi-quantitatively to range from 10 – 170 µg/kg.

A homologous series of internal standards for near universal application in the discovery LC-MS/MS bioanalytical laboratory

When using Liquid Chromatography-Tandem Mass Spectrometry (LC–MS/MS) to quantify In Vivo samples, an internal standard (ISTD) is key in correcting for variability within the sample extraction process and injection volume. Just as important is the ability of the internal standard to identify any matrix effects, which can artificially suppress or enhance the signal of the compound of interest. To properly do this, the internal standard should co-elute with the compound. A common source of potential matrix effects with In Vivo studies is from the excipient(s) used to formulate the compound for dosing. In the world of high-throughput discovery bioanalysis, a lab can quantitate over a hundred compounds each week, many of which are evaluated once, and rarely is a stable-isotope labeled (SIL) internal standard available (the industry gold standard). Finding a suitable and easy-to-use alternative LC–MS/MS method is important to providing high quality data. To overcome this challenge, a homologous series of compounds was synthesized to improve the chromatographic range for co-eluting ISTD’s. This novel mix of internal standards was shown to have key characteristics making it ideal for use as a near universal internal standard mix including but not limited to: they ionize in both positive and negative modes, they are susceptible to signal perturbation from common formulation excipients, and they cover a wide range of retention times.

Chiral Bent‐Shaped Molecules Exhibiting Unusually Wide Range of Blue Liquid‐Crystalline Phases and Multistimuli‐Responsive Behavior

Recently, an unprecedented observation of polar order, thermochromic behavior, and exotic mesophases in new chiral, bent-shaped systems with a -CH3 moiety placed at the transverse position of the central core was reported. Herein, a homologous series of compounds with even-numbered carbon chains from n=4 to 18 were synthesized, in which -Cl was substituted for -CH3 at the kink position and a drastic modification in the phase structure of the bent-shaped molecule was observed. An unusual stabilization of the cubic blue phase (BP) over a wide range of 16.4 °C has been witnessed. Two homologues in this series (1-12 and 1-14) exhibit an interesting phase sequence consisting of BPI/II, chiral nematic, twist grain boundary, smectic A, and smectic X (SmX) phases. The higher homologues (1-16 and 1-18) stabilize the SmX phase enantiotropically over the entire temperature range. Crystal structure analysis confirmed the bent molecular architecture, with a bent angle of 148°, and revealed the presence of two different molecular conformations in an asymmetric unit of compound 1-4. A DFT study corroborated that the -Cl moiety at the central core of the molecule led to an increase in the dipole moment along the transverse direction, which, in turn, facilitated the unusual stabilization of frustrated structures. Crystal polymorphism has been evidenced in three homologues (1-10, 1-12, and 1-14) of the series. On the application of mechanical pressure through grinding, compound 1-10 transformed from a bright yellow crystalline solid to a dark orange-green amorphous solid, which reversed upon dropwise addition of dichloromethane, indicating reversible mechanochromism in this class of compounds. In addition, excellent thermochromic behavior has been observed for compound 1-10 with a controlled temperature-color combination.

Towards Functional Fluorous Surfactants. Synthesis and Spectroscopic Features of Systematically Modified Sugar-Substituted Fluorous 1,2,3-Triazoles

ABSTRACT A library of 10 series of homologous compounds making up a total of 30 new, fluorous 1-substituted 1,2,3-triazol-4-ylmethyl(and ethyl) ether surfactant candidates, with highly systematic variations in substituent position and type, have been synthesised in consistently good yields by processes involving copper(I)-accelerated Huisgen-Meldal dipolar cycloaddition reactions. Each series contains a perfluorobutylethyl, perfluorohexylethyl or perfluorooctylethyl substituents at triazole position N(1) or attached through the triazole ether oxygen, and either a 1-β-D-glucosyl or 6-α-D-galactosyl substituent at the alternative triazole position. Half the library was prepared directly with the sugar components in a protected form (peracetylated glucose derivatives and 1,2:3,4-bisacetonide galactose derivatives) while the other series with unprotected sugars were obtained following a secondary deprotection step by trans-esterification using sodium methoxide or acid catalysed acetal solvation. All the triazoles are candidates for study as fluorous surfactants that are switchable between amphiphilic partner states, hydrophobic in the case of protected sugars and hydrophilic in unprotected sugars. As a prelude to surfactant studies, the NMR spectroscopic characteristics of the newly establish library of compounds were examined. Data were compared and contrasted within and between each series with reference to related literature analogues. Analysis of unprotected 6-galactosyl derivatives was complicated by the well known generation of inseparable, epimeric mixtures of hemiacetal pyranose and furanose products and the general paucity in the literature of NMR spectroscopic data assignments of signals from 1-β-hydroxygalactopyranose compounds. These matters have been addressed in this paper and the comparisons include analyses of unprotected 1'-α- and 1'-β-hydroxy-pyranose derivatives.

Elucidation of Selectivity Reversals for Binary Mixture Adsorption in Microporous Adsorbents.

The adsorption selectivity, Sads, is a key metric that quantifies the efficacy of any adsorbent in mixture separations. It is common practice to use ideal adsorbed solution theory (IAST) for estimating the value of Sads, using unary isotherm data inputs. In a number of experimental investigations, the phenomena of selectivity reversals and adsorption azeotropy (Sads = 1) have been reported in the published literature; such reversals may result from changes in mixture compositions, pressures, or pore loadings. In many cases, IAST is unable to anticipate such selectivity reversals. In this article, configurational-bias Monte Carlo simulations are used to gain insights into the phenomena of selectivity reversals. Two fundamentally different scenarios of selectivity reversals have been identified. In the first scenario, selectivity reversals are caused by inhomogeneous distribution of adsorbates due to preferential location and siting of a guest species in the pore space. For example, CO2 locates preferentially in the side pockets of mordenite and in window regions of DDR, CHA, and LTA zeolites. CO2 also congregates around the extra-framework cations of NaX zeolite. IAST fails to anticipate such selectivity reversals because its development relies on the assumption that the competition between guest species is uniform within the pore space. In the second scenario, selectivity reversals are caused by entropy effects that manifest near pore saturation conditions; the component that is preferentially adsorbed is the one that has the higher packing efficiency. For a homologous series of compounds, the component with the smaller chain length is favored at high pore occupancies. For adsorption of mixtures of alkane isomers within the intersecting channel network of MFI zeolite, the linear isomer is favored on the basis of entropic considerations.

Antifungal Activity of Morpholine and Piperidine Based Surfactants

Abstract Microorganisms have the remarkable capacity to develop resistance to antimicrobial agents. This is of particular concern for fungal pathogens which cause devastating invasive infections with limited treatment options. Thus the need for new antifungal agents is undeniable. This work presents the antifungal properties of four surfactant groups, namely two groups of sulfobetaines and two groups of quaternary ammonium compounds, all morpholine and piperidine derivatives, against drug susceptible or drug resistant Candida albicans and Cryptococcus neoformans. The values of minimum inhibitory and fungicidal concentrations were determined. As follows from the results, the activities of the obtained compounds differed, however the most active agents from each homologous series of compounds, such as P16S3, P16S4 and C16S3, were pointed out.

Synthesis, mesogenic and photoisomerization studies of (E)-4-[(4-pentyloxyphenyl)diazenyl]phenyl alkanoates

ABSTRACTHomologous series of esters of (E)-4-[(4-pentyloxyphenyl)diazenyl]phenol and aliphatic carboxylic acids were synthesized, 5O-m for short. Derivatives with alkyl chains longer than seven carbon atoms are described in this article for the first time. The mesogenic properties and phase transition parameters (temperatures and enthalpies) were measured using a polarizing microscopy and a differential scanning calorimetry. Investigated compounds exhibit occurrence of the enantiotropic nematic phase, despite two derivatives with the longest alkyl chains. One can observe two crystalline phases in two derivatives (5O-6, 5O-7). The presence of the azo group in the homologous series of compounds suggests that the possibility of trans–cis isomerization is controlled by light. Such studies have been carried out and their results suggest that the presence of two trans–cis isomerization mechanisms described as the first-order reaction.

Synthesis and mesomorphic properties and optical behaviour analysis of homologous series azobenzene liquid crystal monomer with polar substituents

ABSTRACT Twenty novel azobenzene liquid crystal micromolecular compounds named ω-[4-(p-substituted azobenzeneoxy carbonyl]acid (X-ABCnA) have been designed and synthesised, followed by studies on the thermal performance and mesomorphic properties of the compounds. The liquid crystal compounds were divided into five homologous series based on the terminal substituents R (R = CH3O, CH3, H, Cl, NO2). In each series, the number of carbons on flexible chain was 4, 6, 8 and 10, respectively. Fourier-transform infrared, proton nuclear magnetic resonance and elementary analysis demonstrated that the structure of the synthesised azobenzene liquid crystal compounds was consistent with the molecular design. The mesomorphic properties were tested, analysed and characterised by using differential scanning calorimetry and polarised optical microscopy. The melting transition (T m) of all the compounds in homologous series with different substituents appeared to decrease with the increase of carbon numbers on flexible chains. The same held true for the temperature of isotropic-mesophase/crystalline transition. The compounds with stronger polarity of terminal substituents were more likely to form broader mesogenic ranges. The liquid crystal compounds discussed in this work can be regarded as a reference for the synthesis of mesogenic arms participating in the synthesis of novel multi-arm liquid crystalline macromolecules and polymers.

Elucidation of the absolute configuration of a tadalafil analogue found as adulterant in a health supplement by mass spectrometry, chiroptical methods and NMR spectroscopy

The chirality of a dipropylaminopretadalafil stereoisomer isolated from a health supplement has been studied. Under high resolution mass spectrometry (HRMS) study, this unknown compound seems to be one of the trans configuration tadalafil analogues i.e. (6S, 12aR) or (6R, 12aS), owing to the same precursor ion at m/z 492 with mass errors within ±2 ppm tolerance and very close retention times. Moreover, the MS2 fragmentation pattern is also very similar to the two trans isomers. Fortunately, the unknown compound can be distinguished from the two trans isomers by enantioselective separation with the use of a chiral column. Further comparison studies with a series of homologous compounds without a diketopiperazine ring on ellipticity and optical rotation support the unknown compound to be in the cis-(6R, 12aR) configuration. The nuclear magnetic resonance (NMR) in one dimensional (1D) and nuclear overhauser effect spectroscopy (NOESY) have affirmed the abovementioned configuration.

Программа «Moments of inertia» для расчёта моментов инерции вращательного движения молекул

The moment of inertia of the rotational motion I, as a descriptor of the spatial structure of the molecule, which determines the properties of a substance, in accordance with the works of recent years, begins to acquire significance in the study of the «structure – property» dependencies, allowing one to describe the change in the properties of compounds in homologous series and address odd homologues. The problem is that there is no universal and transparent method for calculating the moments of inertia of the rotational motion of molecules. Researchers are trying to solve this problem in various ways: presenting the molecule as its carbon chain and calculating the moments of inertia only for it, neglecting the contribution of other atoms, manually calculating the moments of inertia for small simple molecules, based on their estimated geometry, extracting intermediate results from quantum chemical calculations of the program packages like Gaussian or Gamess. We have developed a program for the exact calculation of the moments of inertia, which uses the specification of the exact geometry of the molecule in three-dimensional space using Cartesian coordinates. The program is written on Perl programming language and is available under the GNU General Public License v3.0 (free software). The program uses XYZ files as input data. The principle of the program is to iteratively calculate the inertia moments for all possible positions in the space of the axis of rotation passing through the center of mass of the calculated molecule. The minimum and maximum values of the moments of inertia obtained during the calculation correspond to two perpendicular axes of rotation of the molecule (x and z). The moment of inertia with respect to the third remaining y axis is calculated after finding the canonical equation of the straight axis perpendicular to the found x and z axes.

“Synthesis, Mesomorphic and DFT Studies of Chalcone Derived Room Temperature Liquid Crystal with Presence of Lateral Nitro and N, N-Dimethyl Amino Terminal Group”

In this present article, we wish to report on the liquid-crystalline properties of chalcone-ester based homologous series of compounds having aliphatic chain length in n-alkoxy group (n = 1 to 10, 12, 14, 16, 18). The present series consisted thirteen compounds, in which comp.C1 and C2 shows nonliquid crystalline properties, while comp.C3 to C7 display SmC phase and comp.C8 to C18 exhibits only nematic phase. Textural pattern of presently synthesized compounds are schlieren and threaded type. All this compounds were well characterized by elemental analysis, FT-IR and 1H NMR. Phase transition temperatures of present synthesised compounds were determined by optical polarising microscopy (POM), differential scanning calorimetric (DSC). Detailed XRD investigation endorses the presence of the nematic phase in higher homologues and SmC phase in lower homologues. It is shown that chalcone with ester as linking unit favors a calamitic liquid crystalline behaviour in molecules. To get more insights, the DFT based HOMO, LUMO studies are carried out which supports intramolecular charge transfer interactions in this class of mesogens. Chalconyl ester based compounds C3 to C12 shows antibacterial as well as antifungal activity compared with corresponding standard drugs.

Gradient method transfer after changing the average pore diameter of the chromatographic stationary phase I – One-dimensional sample mixture

Three different approaches designed to transfer gradient methods from a chromatographic column 1 packed with particles (2.7 μm 90 ÅCORTECS-C18 or CORTECS-Triphenyl) to a column 2 packed with the same particles having a larger average pore diameter (APD = 120 Åand 450 Å) are proposed for a one-dimensional sample mixture. Two approaches are based on the variation of the experimental retention plots (lnk vs. the volume fraction, φ, of the strong solvent) with increasing the APD. They lead to so-called “vertical” (vertical shift in column phase ratio, lnϕ2ϕ1) and “horizontal” (horizontal shift in eluent composition, Δφ1 →2) gradient method transfers. The third method is based on in silico predictions of the gradient retention times when considering the actual non-linearity of the retention plots. The adjusted gradient parameters (starting eluent composition, φ0, and temporal gradient steepness, β) are unambiguously determined by minimizing the distance between the calculated and targeted gradient retention times of all the analytes.The performances of the three approaches for gradient method transfer are compared for a sample mixture containing a non-retained compound (thiourea) and a series of five homologous compounds (n-alkanophenones). The ultimate goal is to keep unchanged the gradient retention times of all analytes when changing the APD of the particles. The results show that the in silico transfer systematically outperforms the “horizontal” transfer, which itself outperforms the “vertical” transfer. The first two approaches are the least successful ones because, even for a series of homologous compounds, the linear solvent strength model (LSSM) is only an approximate model and the best shifts in eluent composition that keeps retention factors unchanged are compound-dependent. In the end, the average relative deviations between the observed and targeted gradient retention times are 15.0, 1.7, and 0.4% (90 Åto 120 Åtransfer, C18 chemistry), 5.1, 5.8 and 0.8% (90 Åto 450 Åtransfer, C18 chemistry), 4.8, 0.5, and 0.4% (90 Åto 120 Åtransfer, Triphenyl chemistry), and 10.4, 7.1, and 2.2% (90 Åto 450 Åtransfer, Triphenyl chemistry) for the “vertical”, “horizontal”, and “in silico” gradient method transfers, respectively.

A method for extracting calibrated volatility information from the FIGAERO-HR-ToF-CIMS and its experimental application

Abstract. The Filter Inlet for Gases and AEROsols (FIGAERO) is an inlet specifically designed to be coupled with the Aerodyne High-Resolution Time-of-Flight Chemical Ionization Mass Spectrometer (HR-ToF-CIMS). The FIGAERO-HR-ToF-CIMS provides simultaneous molecular information relating to both the gas- and particle-phase samples and has been used to extract vapour pressures (VPs) of the compounds desorbing from the filter whilst giving quantitative concentrations in the particle phase. However, such extraction of vapour pressures of the measured particle-phase components requires use of appropriate, well-defined, reference compounds. Vapour pressures for the homologous series of polyethylene glycols (PEG) ((H-(O-CH2-CH2)n-OH) for n=3 to n=8), covering a range of vapour pressures (VP) (10−1 to 10−7 Pa) that are atmospherically relevant, have been shown to be reproduced well by a range of different techniques, including Knudsen Effusion Mass Spectrometry (KEMS). This is the first homologous series of compounds for which a number of vapour pressure measurement techniques have been found to be in agreement, indicating the utility as a calibration standard, providing an ideal set of benchmark compounds for accurate characterization of the FIGAERO for extracting vapour pressure of measured compounds in chambers and the real atmosphere. To demonstrate this, single-component and mixture vapour pressure measurements are made using two FIGAERO-HR-ToF-CIMS instruments based on a new calibration determined from the PEG series. VP values extracted from both instruments agree well with those measured by KEMS and reported values from literature, validating this approach for extracting VP data from the FIGAERO. This method is then applied to chamber measurements, and the vapour pressures of known products are estimated.