The seventh blind test of crystal structure prediction: structure generation methods.

A seventh blind test of crystal structure prediction was organized by the Cambridge Crystallographic Data Centre featuring seven target systems of varying complexity: a silicon and iodine-containing molecule, a copper coordination complex, a near-rigid molecule, a cocrystal, a polymorphic small agrochemical, a highly flexible polymorphic drug candidate, and a polymorphic morpholine salt. In this first of two parts focusing on structure generation methods, many crystal structure prediction (CSP) methods performed well for the small but flexible agrochemical compound, successfully reproducing the experimentally observed crystal structures, while few groups were successful for the systems of higher complexity. A powder X-ray diffraction (PXRD) assisted exercise demonstrated the use of CSP in successfully determining a crystal structure from a low-quality PXRD pattern.

A direct analysis method using sheath flow probe electrospray ionisation-mass spectrometry (sfPESI-MS) to detect drug residues from fingerprint forensic gel lifts.

Latent fingerprints at crime scenes are frequently recovered using forensic gel-lifters, which can help to preserve the crime scene and to enhance visualisation of traces such as blood or paint. In addition to providing fingerprint ridge detail, additional chemical information can also be recovered from gel lifts that may prove pertinent to an investigation. However, while DNA and metal ions have been shown to be able to be detected in gel-lifted fingerprints, the determination of other types of chemical information such as the presence of drugs in gel-lifted prints has not been previously shown.

Differentiation of Body Fluid Stains Using a Portable, Low-Cost Ion Mobility Spectrometry Device-A Pilot Study.

The identification and recovery of suspected human biofluid evidence can present a bottleneck in the crime scene investigation workflow. Crime Scene Investigators typically deploy one of a number of presumptive enhancement reagents, depending on what they perceive an analyte to be; the selection of this reagent is largely based on the context of suspected evidence and their professional experience. Positively identified samples are then recovered to a forensic laboratory where confirmatory testing is carried out by large lab-based instruments, such as through mass-spectrometry-based techniques.

Development of a rapid, in-situ analysis method using sheath-flow probe electrospray ionisation-mass spectrometry for the direct identification of cocaine metabolites in dried blood spots.

Rationale: Small amounts of biofluid samples are frequently found at crime scenes; however, existing gold standard methods such as LC-MS frequently require destructive extraction of the sample before a time-consuming analysis which puts strain on forensic analysis providers and can preclude further sample analysis. This study presents the application of sheath-flow probe electrospray ionization-mass spectrometry (sfPESI-MS) to the direct analysis of drug metabolites in dried blood spots (DBS) as a high throughput, minimally destructive alternative.

Methods: A rapid direct analysis method using a sfPESI ionisation source coupled to an Orbitrap Exactive mass spectrometer was applied to detect cocaine metabolites (benzoylecgonine, BZE, cocaethylene, CE, and ecgonine methyl ester, EME) from DBS.

A preliminary investigation of a two-step, non-invasive process to determine chronological deposition order of fingerprints and printed ink on paper.

While traditional techniques have long allowed forensic investigators to positively identify fingermarks on documents of interest, understanding the chronological sequence of events that led to their deposition is still seen as a 'holy grail' for forensic examinations. By way of example, the question of whether a mark is above or below printed text is crucial. The work herein reveals that a novel application of a recently established fingermark development technique readily allows such differentiation.

The importance of dark adaptation for forensic examinations; an evaluation of the Crime-lite Eye™.

Forensic practitioners are recommended to dark adapt their eyes prior to conducting evidential searches in the dark. The dark adaptation process remains poorly standardised across the discipline, with little quantified regarding the benefits of such preparative steps. Herein, we report the findings of a study that recruited 50 participants to assess the effectiveness of the Crime-lite Eye™, a darkness adaptation device developed to assist forensic practitioners both in the laboratory and in field.

Transforming presumptive forensic testing: identification and age estimation of human bodily fluids.

The ability to achieve rapid, identification and age estimation of human bodily fluids can provide valuable information during the investigation of a crime. A novel direct analysis method now permits the rapid identification and age estimation of human bodily fluids for forensic analysis at crime scenes. A thermal desorption surface sampling probe was developed and coupled with a compact mass spectrometer for the direct analysis of volatile organic compound (VOC) profiles of human bodily fluids within two months and in different environmental conditions, without the need for prior sample preparation.

A computational study of doped olivine structured CdGeO: local defect trapping of interstitial oxide ions.

Computational modelling techniques have been employed to investigate defects and ionic conductivity in CdGeO. We show due to highly unfavourable intrinsic defect formation energies the ionic conducting ability of pristine CdGeO is extremely limited. The modelling results suggest trivalent doping on the Cd site as a viable means of promoting the formation of the oxygen interstitial defects.

Visualisation of latent fingermarks on polymer banknotes using copper vacuum metal deposition: A preliminary study.

The UK's recent move to polymer banknotes has seen some of the currently used fingermark enhancement techniques for currency potentially become redundant, due to the surface characteristics of the polymer substrates. Possessing a non-porous surface with some semi-porous properties, alternate processes are required for polymer banknotes. This preliminary investigation explored the recovery of fingermarks from polymer notes via vacuum metal deposition using elemental copper.

Analysis of triacetone triperoxide complexes with alkali metal ions by electrospray and extractive electrospray ionisation combined with ion mobility spectrometry and mass spectrometry.

The complexation of triacetone triperoxide (TATP) with a range of alkali metals has been studied by electrospray ionisation-mass spectrometry yield [M+Cat](+) ions for all of the alkali metals. The formation of [2TATP+Li+LiX](+) (X = Br, Cl) sandwich complexes was also observed. Collision cross- sections for the lithium-containing complexes of TATP were measured by travelling wave ion mobility spectrometry mass spectrometry, and compared well with computationally determined structures.

The recovery of latent text from thermal paper using a simple iodine treatment procedure.

Faded, or actively removed text on thermally printed paper samples may be enhanced and retrieved through the use of a simple iodine fuming procedure. The recovery of printed documentation evidence in this fashion is neither affected by prior fingerprint enhancement techniques (such as ninhydrin or DFO), nor by sample age. This method allows, for the first time, evidence to be obtained from completely faded thermal paper samples (receipts, for example) as well as allowing deliberately removed printed text (a consequence of solvent washing pre-treatment in latent fingerprint enhancement procedures) to be recovered.

Versatile routes to selenoether functionalised tertiary phosphines.

New selenoether functionalised tertiary phosphines, based on aryl (2a, 2b) or alkyl (4) backbones, have been synthesised and characterised. P,Se-chelation has been achieved upon complexation to square-planar Pt(II) (3a) or Pd(II) (3b) metal centres. For 3a and 3b, weak non-covalent M.

Fingerprint and inkjet-trace imaging using disulfur dinitride.

Exposure of fingerprints to S(2)N(2) vapour results in the prints being visually imaged by polymeric (SN)(x) on an unprecedented range of media; in addition, the polymer forms in response to the interaction of S(2)N(2) with traces of inkjet inks, for example the minute amounts left by the contact between printed paper and an envelope.

Sulfimidation of thioether groups--a versatile method for modifying and linking thia/oxa crowns.

Reaction of the mixed thioether/ether crowns [9]aneO2S , [12]aneO3S and [18]aneO4S2 with one mol. equivalent of the aminating agent MSH (o-mesitylsulfonylhydroxylamine) in Et2O results in the formation of the mono-sulfimidated systems {[9]aneO2(S=NH2)}+, {[12]aneO3(S=NH2)}+ and {[18]aneO4S(S=NH2)}+, while using two mol. equivalents of MSH with gives the disulfimidium cation {[18]aneO4(S=NH2)2}2+.

The first use of the free selenimide Ph2Se=NH as a synthon; the synthesis and X-ray crystal structure of [Ph2SeNSePh2][BPh4].

Reaction of o-mesitylsulfonylhydroxylamine (MSH) with Ph(2)Se results in the [Ph(2)SeNH(2)](+) cation; low temperature deprotonation (LDA), bromination (NBS) and then treatment with Ph(2)Se-Na[BPh(4)] generates [Ph(2)SeNSePh(2)][BPh(4)], via the selenimides Ph(2)Se=NH and Ph(2)Se=NBr.

Rapid polymerisation of S2N2 within Na-ZSM-5 channels.

Reaction of S(2)N(2) vapour with Na-ZSM-5 results in rapid polymerisation and inclusion of the resulting (SN)(x) within the zeolite channels.

The reaction of [Bu4N]2[Pd2Br6(Se2N2)] with [14]aneS4; an effective source of the diselenium dinitride unit.

Reaction of [Bu(4)N](2)[Pd(2)Br(6)(Se(2)N(2))] with [14]aneS(4) results in eventual formation of Se(4)N(4); intermediates in this reaction include an air-sensitive insoluble material which reacts with [PtCl(2)(PMe(2)Ph)](2) to give the first example of a platinum adduct of Se(2)N(2) and with [Pd(2)Br(6)](2-) to regenerate the starting material.

Sulfimidation--a new and versatile strategy for the post ring-closure derivatisation of mixed thia/oxa crowns.

Reaction of [18]aneO(5)S with the aminating agent MSH results in the {[18]aneO(5)SNH(2)}+ cation which may be converted through to the linked crown system [({[18]aneO(5)S}(2)N)]+ via deprotonation, bromination and reaction with the parent crown; significantly, despite their positive charge, both systems can coordinate sodium cations to the ether linkages.

The use of the bromosulfimide Ph2S=NBr as nitrogen source in reactions with selenium-based systems.

The N-bromosulfimide Ph(2)S=NBr reacts with a range of selenium sources including, uniquely, elemental selenium itself, to generate the explosive nitride Se(4)N(4).

Synthetic applications of (Me3SiNSN)2E (E = S, Se) in chalcogen-nitrogen chemistry: formation and structural characterization of Cl2TeESN2 (E = S, Se) and [PPh4]2[Pd2(mu-Se2N2S)X4] (X = Cl, Br).

The reaction of (Me3SiNSN)2S with TeCl4 in CH2Cl2 affords Cl2TeS2N2 (1) and that of (Me3SiNSN)2Se with TeCl4 produces Cl2TeSeSN2 (2) in good yields. The products were characterized by X-ray crystallography, as well as by NMR and vibrational spectroscopy and EI mass spectrometry. The Raman spectra were assigned by utilizing DFT molecular orbital calculations.

1lambda(4),4lambda(4),8lambda(4),11lambda(4)-Tetrathiacyclotetradecane-1,4,7,10-tetraylidenetetraaminium tetrakis(2,4,6-trimethylbenzenesulfonate).

Investigations of the reactivity of the thio-crown [14]aneS(4) (1,4,8,11-tetrathiacyclotetradecane) towards the aminating agent o-mesitylsulfonylhydroxylamine have lead to the crystallization of 1lambda(4),4lambda(4),8lambda(4),11lambda(4)-tetrathiacyclotetradecane-1,4,7,10-tetraylidenetetraaminium tetrakis(2,4,6-trimethylbenzenesulfonate), C10H28N4S(4)4+.4C9H11O3S-. The compound crystallizes in a centrosymmetric space group, with half a formula unit in the asymmetric unit.

The first examples of metal-mediated addition of a phosphorus imine to nitriles; the preparation and X-ray crystal structures of [PtCl4{NH=C(Et)N=PPh3}2] and [PtCl2(EtCN){NH=C(Et)N[double bond, length as m-dash]PPh3}].

Imino(triphenyl)phosphorane, Ph3P=NH (1), reacts with nitrile complexes of Pt(IV) to generate hydrolytically sensitive [PtCl4{NH=C(R)N=PPh3}2](R=Me 2a, Et 2b, Ph 2c), and with the Pt(II) complex [PtCl2(EtCN)2] to give [PtCl2(EtCN){NH=C(Et)N=PPh3}](3) and [PtCl2{NH=C(Et)N=PPh3}2](4); X-ray crystallography performed upon (2b) and (3) confirms the presence of an imine/nitrile addition ligand bound by the terminal nitrogen.

Polymorphism in ammonium 2,4,6-trimethylbenzenesulfonate.

During investigations into sulfide- and selenide-amination reactions using the aminating agent o-mesitylsulfonylhydroxylamine, the monoclinic, (I), and orthorhombic, (II), polymorphs of ammonium 2,4,6-trimethylbenzenesulfonate, NH4+.C9H11O3S-, have been crystallized. Investigation of the hydrogen-bonding motifs within the two polymorphs shows that both contain N+-H.