SS Configuration Research Articles

Crystal structure of 1-(1-chloroethyl)-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinolinium chloride

1-(1-Chloroethyl)-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline was synthesized through the reaction of homoveratrylamine with racemic lactic acid. The formation of two enantiomers, RR and SS, was detected by performing X-ray diffraction analysis on their chloride salts. The asymmetric unit of the crystal consists of a C13H19ClNO2 + molecular cation and a Cl− anion. Two protonated enantiomers of the title compound, with RR and SS configurations of the chiral atoms, are connected into hydrogen-bonded dimers bridged by Cl− anions. Weak C—H...Cl interactions lead to the formation of a chain running along the a-axis direction of the unit cell, which corresponds to the longest dimension (the preferential growth direction) of the needle-shaped monocrystal. The crystal studied was refined as a two-component twin.

Effect of CFRP strip tie configurations on the behavior of GFRP reinforced concrete columns under different loading conditions

This study presents the results of an experimental program on the behavior of concrete specimens reinforced longitudinally with glass fiber-reinforced polymer (GFRP) bars and transversely with square, square-square, and square-circular (S, SS, and SC) configurations of carbon fiber-reinforced polymer strip (CS) ties under different loading conditions. Nine specimens were tested as columns under concentric and eccentric axial loads and three specimens were tested as beams under four-point bending. The experimental results demonstrated that specimens reinforced with the SC configuration of CS ties exhibited superior load-carrying capacity and deformability compared to specimens reinforced with the S or SS configurations when subjected to concentric and eccentric axial loads. Also, the contribution of GFRP bars in the maximum axial load sustained by specimens under concentric axial load is higher for specimens reinforced with SC configuration of CS ties than for specimens reinforced with S and SS configurations of the CS ties.

THEORETICAL EVALUATION OF DISTRICT HEATING AND COOLING NETWORKS CONNECTED TO HEAT PUMPS

This article conducts a comprehensive theoretical analysis containing operational, carbon footprint, and economic aspects of a medium-high temperature heat pump (HP) employing R-1234ze(E). The study contains a total of three scenarios, where the first (single stage/two stage (SS/TSC)) scenario uses waste heat for district heating. The second (SS/TSC) scenario produces heating and cooling for district heating and cooling. The third (TSC) scenario uses heat from the district heating network (DHN) for conventional boiler applications. Regarding the energy analysis, the internal heat exchanger (IHX) presents a positive impact across all scenarios. Moreover, the TSC configuration exhibits a lower coefficient of performance (COP) than SS for scenario 1, and higher for scenario 2. The first scenario (SS) results in the highest COP (4.1), due to presenting the lowest compression ratio among the three scenarios. From a carbon footprint perspective, compared to a natural gas boiler, the first scenario achieves the highest reduction in emissions. Regarding the economic analysis, TSC configurations exhibit higher costs than SS ones. The first (SS) and second (SS) scenarios present the lowest capital expenditure (CAPEX), 35134 € and 44371 €, respectively. Economic viability analysis reveals that only the first and second scenarios with SS configuration are feasible.

DFT investigation of the mechanism and role of N-heterocyclic carbene (NHC) in constructing asymmetric organosilanes using NHC-catalyzed [4+2] cycloaddition reaction.

Herein, the mechanism and origin of stereoselectivity for the asymmetric [4+2] cycloaddition between (E)-3-(p-tolyl)acrylaldehyde (R1) and phenyl-3-(trimethylsilyl)prop-2-en-1-one (R2) in the presence of an N-heterocyclic carbene (NHC) were theoretically scrutinized. The desirable catalytic cycle is characterized by five steps: (1) the coupling reaction of the NHC catalyst with R1, the formation of the Breslow and enolate intermediates in the second and third steps, (4) the formal [4+2] cycloaddition reaction to form the stereoselective C-C bond, and (5) the regeneration of NHC to obtain asymmetric organosilanes. In the most energetically favorable pathway, the formation of the enolate intermediate exhibits the highest energy barrier of about 19.48 kcal mol-1 (Re-TS2BA) and is the rate-determining step. The [4+2] cycloaddition reaction is the stereoselectivity-determining step forming the chiral C-C bond with RR, RS, SR and SS configurations, among which RS is the most desirable configuration. The origin of stereoselectivity was investigated using distortion energy analysis. The first and fourth steps helped in investigating the effects of electron-donating (Me) and electron-withdrawing (Cl) groups on cinnamaldehyde. Conceptual DFT (CDFT) analysis was carried out to confirm the critical role of the NHC catalyst as a Lewis base during the reaction processes.

Electrochemical Degradation of Toluene Using TiO2 Nanotubes

Toluene is a solvent widely used to produce paints, thinners, varnishes, and adhesives, as well as an octane rating improvement additive in gasoline. This compound can, unfortunately, be released into the environment in car exhaust fumes or when products containing toluene are used. Continuous exposure at high levels can cause permanent brain damage in animals. TiO2 nanotubes (TiO2,nt) increase the surface/volume ratio, as well as efficient electron transport, in the metallic substrate of Ti, enhancing the electrochemical degradation of organic compounds such as toluene.An anodizing procedure has been performed to synthesize TiO2 in the present work. The team varied two anodizing operating conditions: potential (10, 20, 30, 40, and 50 V) and cathode material (titanium, Ti, and stainless-steel, SS) to achieve desirable results. The synthesized electrodes were characterized by Raman spectroscopy to identify the different crystallographic phases. We identified the presence of the three typical phases of TiO2 (anatase, rutile, and brookite), mainly in the synthesized electrodes at 30 V (using Ti and SS as the cathode). More significant intensity signals were observed than those corresponding to the anatase and rutile phases. Additionally, the different electrodes were analyzed by scanning electron microscopy with microanalysis (SEM-EDX) to identify the external morphology and validate their chemical composition. The toluene was hydrolyzed in ethanol with the different synthesized electrodes (Ci = 1.0 ppm, E = 2.0 V, t = 180 min, n = 150 rpm, cathode = Ti or SS). Toluene removal was monitored by gas chromatography with detector BID (CG-BID). Results indicate that the electrodes synthesized at 30 V show the highest removal efficiencies in a minimal time. The TiO2,nt|Ti synthesized using the TiO2,nt|Ti ||Ti configuration showed a toluene removal of 94.53 % in 12 min. In contrast, for the TiO2,nt|Ti synthesized using the TiO2,nt|Ti||SS configuration showed a 100 % toluene removal achieved in 6 min.In conclusion, the best result for synthesizing the TiO2,nt|Ti reactive nanotube-rich surface was the configuration using stainless steel as the cathode (TiO2,nt|Ti||SS), applying a potential of 30 V during the 15 min anodizing treatment. This modified surface showed the highest toluene removal efficiency, 100 %, at 6 min when this VOC was dissolved in ethanol with 0.1 M KCl as the supporting electrolyte. This result is due to the anatase and rutile phases of TiO2, as verified with Raman spectroscopy. The corresponding stoichiometric relationship of two atoms of oxygen and one atom of titanium in the TiO2 nano-tubes when analyzed using SEM-EDX. After the electrolysis of toluene, the anatase phase was lost.

One-step adaptive reconfiguration technique for partial shaded photovoltaic array

The performance of a photovoltaic (PV) array greatly depends on partial shading conditions, which can be diminished by careful planning and positioning of PV modules during installation to avoid self-shading. However, partial shading caused by nearby buildings, dust, and snow cannot be completely avoided. One of the approaches to reduce the effects of partial shading is the reconfiguration technique. However, the reconfiguration increases the length of the wire and system complexity. This study proposes an adaptive reconfiguration technique for a 4x4 PV array with reduced complexity and better shade dispersion. The effectiveness of the proposed reconfiguration technique is implemented and tested on a 4x4 total-cross-tied PV array in a MATLAB Simulink environment. In the proposed configuration, the switching matrix connects the fixed and adaptive part of the PV array, in such a way that the switches can connect the PV module of the next column by shifting downwards and shifting upwards. A comprehensive analysis of proposed reconfiguration is carried out and its performance is compared with existing fixed and dynamic reconfiguration techniques in terms of performance parameters. The study result shows that the proposed reconfiguration technique delivers superior performance compared to existing fixed and dynamic reconfiguration techniques in terms of better shade dispersion, enhanced performance and reduced complexity. For the LC shade pattern, the proposed BSSU technique has obtained improved PE of 48%, 31%, 15% and 9% compared to CMA, TCT, ADR and SS configurations. Experimental verification is carried out to demonstrate the superiority of the proposed reconfiguration technique.

Theoretical Study on Cooperation Catalysis of Chiral Guanidine/ Copper(I) in Asymmetric Azide-Alkyne Cycloaddition/[2 + 2] Cascade Reaction.

Density functional theory (DFT) calculations with BP86-D3(BJ) functionals were employed to reveal the mechanism and stereoselectivity of chiral guanidine/copper(I) salt-catalyzed stereoselective three-component reaction among N-sulfonyl azide, terminal alkyne, and isatin-imine for spiroazetidinimines that was first reported by Feng and Liu (Angew. Chem. Int. Ed. 2018, 57, 16852-16856). For the noncatalytic cascade reaction, the denitrogenation to generate ketenimine species was the rate-determining step, with an activation barrier of 25.8-34.8 kcal mol-1. Chiral guanidine-amide promoted the deprotonation of phenylacetylene, generating guanidine-Cu(I) acetylide complexes as active species. In azide-alkyne cycloaddition, copper acetylene coordinated to the O atom of the amide moiety in guanidium, and TsN3 was activated by hydrogen bonding, affording the Cu(I)-ketenimine species with an energy barrier of 3.5∼9.4 kcal mol-1. The optically active spiroazetidinimine oxindole was constructed via a stepwise four-membered ring formation, followed by deprotonation of guanidium moieties for C-H bonding in a stereoselective way. The steric effect of the bulky CHPh2 group and chiral backbone in the guanidine, combined with the coordination between the Boc group in isatin-imine with a copper center, played important roles in controlling the stereoselectivity of the reaction. The major spiroazetidinimine oxindole product with an SS configuration was formed in a kinetically more favored way, which was consistent with the experimental observation.

Comparison of standard versus reconstruction proximal interlocking screw configurations for antegrade intramedullary nail fixation of femoral shaft fractures

BackgroundThe standard proximal interlocking screw (SS) configuration for antegrade intramedullary nail (IMN) fixation of femoral shaft fractures is lateral to medial or from the greater to less trochanter. Some authors argue for the routine use of the reconstruction screw (RS) configuration (oriented up the femoral neck) instead to prevent femoral neck complications. The purpose of this study was to compare a matched cohort of patients receiving these screw configurations and subsequent complications. MethodsA retrospective review of two urban level-one trauma centers identified adults with isolated femoral shaft fractures undergoing antegrade IMN. Patients with RS and SS configurations were matched 1:1 by age, sex, fracture location, and AO classification in order to compare complications. Results130 patients with femoral shaft fractures were identified. SS and RS configurations were used in 83 (64%) and 47 (36%) patients. 30 patients from each group were able to be matched for analysis. The RS and SS group did not differ in age, fracture location, AO classification, operative time, or number of distal interlocking screws. The RS group had fewer open fractures and were more likely to have two proximal screws. There were 7 complications, including 5 nonunions and 2 delayed unions, with no detectable difference between RS vs. SS groups (10% vs 13%, Proportional difference −3%, 95% confidence interval (CI) −30 to 14%, p = 0.1). There were no femoral neck complications in the entire cohort of 130 patients. On multivariate analysis none of the variables analyzed were independently associated with the development of complications. ConclusionsIn this matched cohort of patients with femoral shaft fractures undergoing antegrade IMN fixation, RS and SS configurations were associated with a similar number of complications and no femoral neck complications. The SS configuration remains the standard for antegrade IMN femoral shaft fixation. Level of evidenceLevel III, Retrospective cohort study.

A Double Swath Configuration for Improving Throughput and Accuracy of Trait Estimate from UAV Images.

Multispectral observations from unmanned aerial vehicles (UAVs) are currently used for precision agriculture and crop phenotyping applications to monitor a series of traits allowing the characterization of the vegetation status. However, the limited autonomy of UAVs makes the completion of flights difficult when sampling large areas. Increasing the throughput of data acquisition while not degrading the ground sample distance (GSD) is, therefore, a critical issue to be solved. We propose here a new image acquisition configuration based on the combination of two focal length (f) optics: an optics with f = 4.2 mm is added to the standard f = 8 mm (SS: single swath) of the multispectral camera (DS: double swath, double of the standard one). Two flights were completed consecutively in 2018 over a maize field using the AIRPHEN multispectral camera at 52 m altitude. The DS flight plan was designed to get 80% overlap with the 4.2 mm optics, while the SS one was designed to get 80% overlap with the 8 mm optics. As a result, the time required to cover the same area is halved for the DS as compared to the SS. The georeferencing accuracy was improved for the DS configuration, particularly for the Z dimension due to the larger view angles available with the small focal length optics. Application to plant height estimates demonstrates that the DS configuration provides similar results as the SS one. However, for both the DS and SS configurations, degrading the quality level used to generate the 3D point cloud significantly decreases the plant height estimates.

Mechanism and regio- and stereoselectivity in an NHC-catalyzed Mannich/lactamization domino reaction.

Density functional theory (DFT) calculations (M06-2X) have been employed to disclose the mechanisms and regio- and stereo-selectivities of the N-heterocyclic carbene (NHC)-catalyzed reaction of 2-benzothiazolimines and α-chloroaldehydes. The preferred mechanism is initiated by the nucleophilic attack of NHC on α-chloroaldehyde (first step), followed by 1,2-proton transfer which was assisted by the Brønsted acid DABCO·H+ to generate the Breslow intermediate (second step). The cleavage of the C-Cl bond (third step) and deprotonation (fourth step) form the enolate intermediate. This further reacts with 2-benzothiazolimine which leads to the formation of a new C-C bond (fifth step). Subsequent cyclization takes place via the formation of a new C-N bond (sixth step). Catalyst regeneration completes the whole catalytic cycle and affords the final product (seventh step). The DFT results indicate that the fifth step determines the stereochemistry of the reaction and leads to benzothiazolopyrimidinone with the SS configuration, which agrees well with experimental observations. Intramolecular cyclization is found to be the regioselectivity-determining step, for which the [4+2] annulation pathway is more preferred than that via [2+2] annulation, which again agrees well with experimental observations. Based on the mechanism proposed, the origins of regio- and stereoselectivities have also been investigated by performing distortion/interaction, natural bond orbital (NBO) and non-covalent interaction (NCI) analyses. The mechanistic insights gained in this work should be helpful in the rational design of potential catalysts for analogous reactions.

THEORETICAL ANALYSIS OF THE STRUCTURE OF CHIRAL JASMONIC ACID

Jasmonic acid, also known as jasmonates, (JA), a molecule formed by the oxygenation of fatty acids, is an organic compound and is found in many plants, especially jasmine. The conformation of this compound is found according to the location in the chiral centers. In this study, the molecular structure of JA (labeled C-4 and C-5 in this study) which has two chiral centers was investigated by DFT and TD-DFT methods. These structures have been found to have RR, RS and SS configurations relative to their chiral centers. Each configuration has cis and trans conformations depending on the orientation of the chain groups attached to the five atom ring. The minimum energies of each conformation were calculated with DFT/B3LYP/6-311++G(d,p) method and the structures of their stable form were drawn. JA_RR_trans conformer was found most stable than the other conformers. Excited state energies were calculated using TD-DFT calculations and also HOMO-LUMO energy gaps were found for all chiral conformers.

Mechanisms of phosphine‐catalyzed [4 + 3] annulation of allenoates with C, N‐cyclic azomethine imines: A DFT investigation

AbstractIn this article, mechanisms of phosphine‐catalyzed [4 + 3] annulation of allenoates with C, N‐cyclic azomethine imines have been investigated using density functional theory. The catalytic cycle for the title reaction consists of five steps. Namely, the first step is the nucleophilic addition of phosphine catalyst, the second one is the CC bond formation, the third one is the proton transfer process, and the next one is the ring‐closure process, the last one is dissociation of the catalyst and the product generation. The calculated results indicate that the nucleophilic addition of phosphine catalyst is rate‐determining. With the use of Cat as the chiral catalyst, optically active products were obtained in good yields with excellent enantioselectivities while the CC bond formation is stereoselectivity‐determining. Furthermore, the theoretically predicted the main product is SS configuration, which is in good agreement with the experimental results. The special role of the catalysts and origin of stereoselectivity was also identified by NBO, GRI, and FMO analyses. This work might be helpful for understanding the significant roles of phosphine catalyst and thus provide valuable insights on the rational design of potential catalysts for this kind of reactions.

Heterogeneous Capillary Interactions of Interface-Trapped Ellipsoid Particles Using the Trap-Release Method.

Heterogeneous capillary interactions between ellipsoid particles at the oil-water interface were measured via optical laser tweezers. Two trapped particles were aligned in either tip-to-tip (tt) or side-to-side (ss) configurations via the double-trap method and were released from the optical traps, leading to particle-particle attractions due to the capillary forces caused by quadrupolar interface deformation. On the basis of image analysis and calculations of the Stokes drag force, the capillary interactions between two ellipsoid particles with the same aspect ratio (E) were found to vary with the particle pairs that were measured, indicating that the interactions were nondeterministic or heterogeneous. Heterogeneous capillary interactions could be attributed to undulation of the interface meniscus due to chemical and/or geometric particle heterogeneity. The power law exponent for the capillary interaction Ucap ≈ r-β was found to be β ≈ 4 and was independent of the aspect ratio and particle configuration in long-range separations. Additionally, with regard to the tt configuration, the magnitude of the capillary force proportionally increased with the E value (E > 1) when two ellipsoid particles approached each other in the tt configuration.

Investigation of strut-ramp injector in a Scramjet combustor: Effect of strut geometry, fuel and jet diameter on mixing characteristics

The strut-based injector has been found to be one of the most promising injector designs for a supersonic combustor, offering enhanced mixing of fuel and air. The mixing and flow field characteristics of the straight (SS) and Tapered strut (TS), with fixed ramp angle and height at freestream Mach number 2 in conjunction with fuel injection at Mach 2.3 have been investigated numerically and reported. In the present investigation, hydrogen (H2) and ethylene (C2H4) are injected in oncoming supersonic flow from the back of the strut, where jet to freestream momentum ratio is maintained at 0.79 and 0.69 for H2 and C2H4, respectively. The predicted wall static pressure and species mole fractions at various downstream locations are compared with the experimental data for TS case with 0.6 mm jet diameter and found to be in good agreement. Further, the effect of jet diameter and strut geometry on the near field mixing in strut ramp configuration is discussed for both the fuels. The numerical results are assessed based on various parameters for the performance evaluation of different strut ramp configurations. The SS configuration for both the injectant has been found to be an optimum candidate; also it is observed that for higher jet diameter larger combustor length is required to achieve satisfactory near field mixing.

Theoretical investigations towards the [4+2] cycloaddition of ketenes with 1-azadienes catalyzed by N-heterocyclic carbenes: mechanism and stereoselectivity

This present work reported a detailed DFT study to the reaction mechanism and stereoselectivities of the NHC-catalyzed [4+2] cycloaddition of ketenes with 1-azadienes. The calculated results reveal that the ‘ketene-first’ mechanism is more energetically favorable than the ‘azadiene-first’ one, and the cycloaddition step is demonstrated to be both the rate- and stereoselectivity-determining step. The Gibbs free energy barrier to afford the product in SS configuration is lower than those in other configurations, which is well consistent with the experimental results. Analyses to the distortion–interaction energies of two key species and the components of the free energy barriers of the step in which the stereocenters generate were conducted, and it was concluded that stereoseletivities of the reaction should originate from differences of enthalpy barriers via the four transition state isomers, rather than the distinctions of barriers stemming from entropy penalties.

Selection preserves Ubiquitin Specific Protease 4 alternative exon skipping in therian mammals.

Ubiquitin specific protease 4 (USP4) is a highly networked deubiquitinating enzyme with reported roles in cancer, innate immunity and RNA splicing. In mammals it has two dominant isoforms arising from inclusion or skipping of exon 7 (E7). We evaluated two plausible mechanisms for the generation of these isoforms: (A) E7 skipping due to a long upstream intron and (B) E7 skipping due to inefficient 5′ splice sites (5′SS) and/or branchpoint sites (BPS). We then assessed whether E7 alternative splicing is maintained by selective pressure or arose from genetic drift. Both transcript variants were generated from a USP4-E7 minigene construct with short flanking introns, an observation consistent with the second mechanism whereby differential splice signal strengths are the basis of E7 skipping. Optimization of the downstream 5′SS eliminated E7 skipping. Experimental validation of the correlation between 5′SS identity and exon skipping in vertebrates pinpointed the +6 site as the key splicing determinant. Therian mammals invariably display a 5′SS configuration favouring alternative splicing and the resulting isoforms have distinct subcellular localizations. We conclude that alternative splicing of mammalian USP4 is under selective maintenance and that long and short USP4 isoforms may target substrates in various cellular compartments.

Stereodivergent Synthesis of Iminosugars from Stannylated Derivatives of (S)-Vinylglycinol

An original access to iminosugars from a cis/trans mixture of stannylated oxazolidinones 5 is reported. The dehydropiperidines 7-trans and 7-cis were obtained stereoselectively with an RS and SS configuration depending on the order of the Sn-Li transmetalation (followed by electrophilic trapping) and of the ring closing metathesis reactions due to the stereoselective epimerization of the α-aminoanion intermediate. The dehydropiperidines 7-trans and 7-cis were subsequently used for the synthesis of enantiopure homonojirimycin analogs.

Separation of proteins using sandwich membranes

The effect of sandwich configurations of paired ultrafiltration membranes on the transmission and rejection of proteins were evaluated using various sandwich arrangements. Data is presented for the fractionation of BSA and myoglobin, and for that of lysozyme and myoglobin. Two membranes were sandwiched together in several different configurations without spacer. The sandwich configurations were known as SS-sandwich, BS-sandwich, BB-sandwich and SB-sandwich, where S indicates that the skin layer faces the feed and B indicates that the support layer faces towards the feed. The result of single membrane transmission was compared with the transmission of the various sandwich arrangements. Interestingly not having a skin layer on top and in contact with the feed (as in BS and BB sandwich configurations) was useful for enhancing protein transmission whilst SS and SB configurations can be used to increase protein rejection. For the separation of lysozyme and myoglobin, a selectivity value of 9 was found for S, SS and SB configurations The effect of sandwich membranes varies not only with MWCO but also, to a small extent, with different types of membrane material. For example, the transmission of both proteins using single membranes is comparatively higher than the sandwich membrane for RC and PES membranes, but this was not found to be so for YM membranes.

The Supramolecular Isomerism Based on Argentophilic Interactions: The Construction of Helical Chains with Defined Right-Handed and Left-Handed Helicity

The reactions of racemic and enantiopure macrocyclic compounds [Ni(alpha-rac-L)](ClO(4))(2) (containing equal amounts of SS and RR enantiomers), [Ni(alpha-SS-L)](ClO(4))(2), and [Ni(alpha-RR-L)](ClO(4))(2) with K[Ag(CN)(2)] in acetonitrile/water afford three 1D helical chains of {[Ni(f-rac-L)][Ag(CN)(2)](2)}(n) (1), {[Ni(f-SS-L)](2)[Ag(CN)(2)](4)}(n) (Delta-2), and {[Ni(f-RR-L)](2)[Ag(CN)(2)](4)}(n) (Lambda-2); one dimer of [Ni(f-rac-L)][Ag(CN)(2)](2) (3); and one trimer of [Ni(f-rac-L)Ag(CN)(2)](3).(ClO(4))(3) (4) (L = 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane). Compounds 1, Delta-2, Lambda-2, and 3, which are supramolecular isomers, are constructed via argentophilic interactions. In 1, [Ni(f-RR-L)][Ag(CN)(2)](2) enantiomers alternately connect with [Ni(f-SS-L)][Ag(CN)(2)](2) enantiomers through intermolecular argentophilic interactions to form a 1D meso-helical chain, and the 1D chains are further connected through the interchain hydrogen bonds to generate a 2D network. When chiral [Ni(alpha-SS-L)](ClO(4))(2) and [Ni(alpha-RR-L)](ClO(4))(2) were used as building blocks, two supramolecular stereoisomers of Delta-2 and Lambda-2 were obtained, which show the motif of homochiral right-handed and left-handed helical chains, respectively, and the 1D homochiral helical chains are linked by the interchain hydrogen bonds to form a 3D structure. In 3, a pair of enantiomers of [Ni(f-RR-L)][Ag(CN)(2)](2) and [Ni(f-SS-L)][Ag(CN)(2)](2) connect with each other through intermolecular argentophilic interactions to form a dimer. The reaction of [Ni(alpha-rac-L)](ClO(4))(2) with K[Ag(CN)(2)] in acetonitrile gives a trimer of 4; each trimer is chiral with unsymmetrical RR, RR, and SS, or RR, SS, and SS configurations. The homochiral nature of Delta-2 and Lambda-2 was confirmed by the results of solid circular dichroism spectra measurements. The solid samples of 1-4 show strong fluorescent emissions at room temperature.

(S-Methylcysteinato)(η5-pentamethylcyclopentadienyl)iridium(III) trifluoromethanesulfonate hemihydrate

The cation of the title compound, [Ir(C10H15)(C4H8NO2S)](CF3SO3)·0.5H2O, contains a half-sandwich [Ir(C5Me5)]2+ fragment, the IrIII atom of which is coordinated by the tridentate S-methyl­cysteinate ligand (S-MecysO) in a κ3N,O,S manner. An RIr configuration is observed for the transition metal and an SS configuration for the chiral thio­ether S atom.