High-resolution IR Spectroscopy Research Articles

4-(7-Bromobenzo[d][1,2,3]thiadiazol-4-yl)morpholine

Dibromoderivatives of benzofused chalcogen-nitrogen heterocycles are important precursors in the synthesis of various photovoltaic materials. 4,7-Dibromobenzo[d][1,2,3]thiadiazole is a practically unexplored compound in this series. In this communication, it was shown that the nucleophilic substitution of 4,7-dibromobenzo[d][1,2,3]thiadiazole with morpholine gave selectively 4-substituted product—4-(7-bromobenzo[d][1,2,3]thiadiazol-4-yl)morpholine. The structure of the newly synthesized compound was established by means of elemental analysis, high resolution mass-spectrometry, 1H, 13C NMR, and IR spectroscopy, mass-spectrometry, and X-ray analysis.

Exploring the next step in micro-solvation of CO in water: Infrared spectra and structural calculations of (H2O)4-CO and (D2O)4-CO.

We extend studies of micro-solvation of carbon monoxide by a combination of high-resolution IR spectroscopy and ab initio calculations. Spectra of the (H2O)4-CO and (D2O)4-CO pentamers are observed in the C-O stretch fundamental region (≈2150 cm-1). The H2O containing spectrum is broadened by predissociation, but that of D2O is sharp, enabling detailed analysis that gives a precise band origin and rotational parameters. Ab initio calculations are employed to confirm the assignment to (water)4-CO and to determine the structure in which the geometry of the (water)4 fragment is a cyclic ring very similar to the isolated water tetramer. The CO fragment is located "above" the ring plane, with a partial hydrogen bond between the C atom and one of the "free" protons (deuterons) of the water tetramer. Together with the previous results on D2O-CO, (D2O)2-CO, and (D2O)3-CO, this represents a probe of the four initial steps in the solvation of carbon monoxide at a high resolution.

Metal-Micelle Cooperativity: Phosphine Ligand-Free Ultrasmall Palladium(II) Nanoparticles for Oxidative Mizoroki-Heck-type Couplings in Water at Room Temperature.

The amphiphile PS-750-M generates stable, phosphine ligand-free, and catalytically active ultrasmall Pd(II) nanoparticles (NPs) from Pd(OAc)2, preventing their precipitation, polymerization, and oxidation state changes. PS-750-M directly interacts with Pd(II) NP surfaces, as confirmed by high-resolution mass spectrometry and IR spectroscopy, resulting in their high stability. The Pd cations in NPs are most likely held together by hydroxides and acetate ions. The NPs were characterized by HRTEM, revealing their morphology and particle size distribution, and by HRMS and IR, providing evidence for NP–amphiphile interaction. The NP catalytic activity was examined in the context of oxidative Mizoroki–Heck-type couplings in water at room temperature. Hot filtration, hot extraction, and three-phase tests indicate heterogeneous catalysis occurring at the micellar interface rather than homogeneous catalysis occurring in the solution. NMR studies indicate that the catalytic activity stems from metal cation−π interactions of the styrene along with transmetalation by the arylboronic acid, followed by insertion and β-H elimination to furnish the coupled product along with the reoxidation of Pd by benzoquinone to complete the catalytic cycle. This method is very mild and sustainable, both in terms of NP synthesis and subsequent catalysis, and shows broad substrate scope while circumventing the need for organic solvents for this important class of couplings.

High-Resolution IR Spectroscopy in Low-Temperature Matrices. Structure of Fundamental Absorption Bands of SiH4 in Nitrogen and Argon Matrices

High-Resolution IR Spectroscopy in Low-Temperature Matrices. Structure of Fundamental Absorption Bands of SiH4 in Nitrogen and Argon Matrices

Ethyl 11a,12-Dihydrobenzo[b]benzo[5,6][1,4]oxazino[2,3-e][1,4]oxazine-5a(6H)-carboxylate

The 11a,12-dihydrobenzo[b]benzo[5,6][1,4]oxazino[2,3-e][1,4]oxazine heterocyclic system has been used in the construction of heteropropellanes, which attracted much attention not only on the possible modification of drugs, but also for novel materials with unusual and important physical properties. In this communication, the reaction of ethyl 2-(hydroxyimino)propanoate 1 with disulfur dichloride and o-aminophenol, which gave ethyl 11a,12-dihydrobenzo[b]benzo[5,6][1,4]oxazino[2,3-e][1,4]oxazine-5a(6H)-carboxylate in moderate yield, was described. The structure of the newly synthesized compound was established by means of elemental analysis, high resolution mass-spectrometry, 1H, 13C NMR and IR spectroscopy, mass-spectrometry and X-ray analysis.

8-(Pyrimidin-2-yl)-1,2,3,4,5,6,7,8-heptathiazocane

Heptasulfur imides substituted by hereterocycle may be of interest as biologically active compounds. In this communication, the reaction of pyrimidin-2-amine 1 with disulfur dichloride was carefully investigated to give 8-(pyrimidin-2-yl)-1,2,3,4,5,6,7,8-heptathiazocane in good yield. The structure of the newly synthesized compound was established by means of elemental analysis, high resolution mass-spectrometry, 1H, 13C NMR and IR spectroscopy and mass-spectrometry.

Synthesis and Properties of C,N-Chelated Carbene Complexes of Palladium(II) with 2-Aminobenzo[d]thiazole Fragment

The reaction of bis(cyclohexylisocyanide) complex of Pd(II) with substituted benzo[d]thiazole-2-amines in the presence of triethanolamine as the base has lead to the formation of deprotonated C,N-chelated carbene complexes with a structure similar to that described previously for the products of the reaction with unsubstituted benzo[d]thiazole-2-amine. The complexes have been isolated and characterized using high-resolution mass spectrometry, IR and NMR spectroscopy (1H, 13C{1H}, 1H-1H COSY, 1H-1H NOESY, 1H-13C HSQC, 1H-13C HMBC). The resulting complexes have exhibited moderate antibacterial activity against sensitive strains of gram-negative bacteria E. coli (C600) and P. fluorescens (P218), gram-positive bacteria S. aureus (ATCC-25923) and B. subtillis (B-3142D) as well as fungi C. albicans (401/NCTC-885-653).

8,18-Dithia-1,4,11,14-tetraazapentacyclo[11.7.0.03,11.05,9.015,19]icosa-3,5(9),6,13,15(19),16-hexaene-10,20-dione

4H-3λ2-Thieno[3,2-d]pyrimidin-4-one derivatives are of interest as biologically active compounds. In this communication, 2-(chloromethyl)-4H-3λ2-thieno[3,2-d]pyrimidin-4-one (1) was investigated in the reaction with ammonia, potassium phthalimide, and other basic agents. The dimerization product—8,18-dithia-1,4,11,14-tetrazapentacyclo[11.7.0.03,11.05,9.015,19]icosa-3,5(9),6,13,15(19),16-hexaene-10,20-dione was formed in the reaction with potassium phthalimide in DMF, by heating at 110 °C for 5 h. The structure of the newly synthesized compound was established by means of elemental analysis, high resolution mass-spectrometry, 1H, 13C NMR, and IR spectroscopy, and mass-spectrometry.

3,6-Dibromopyridazine-4,5-diamine

Dihalogenated derivatives of 1,2,5-chalcogenadiazoles fused with benzene or heterocyclic rings are of interest as starting compounds for photovoltaic materials. The 1,2,5-chalcogenadiazole ring in these heterocycles was most commonly prepared from the corresponding ortho-diamine moiety. In this communication, 3,6-dibromopyridazine-4,5-diamine was prepared via the reaction of 4,7-dibromo[1,2,5]thiadiazolo[3,4-d]pyridazine with sodium methoxide in THF by heating at reflux for four hours. The structure of the newly synthesized compound was established by means of high resolution mass-spectrometry, 1H, 13C-NMR and IR spectroscopy, and mass-spectrometry.

Coupling of Bis(xylylisocyanide) Palladium(II) Complex with 1,2,4-Thiadiazole-5-amines

The coupling of bis(xylylisocyanide) complex of Pd(II) with 1,2,4-thiadiazole-5-amines leads to the formation of an equilibrium mixture of the binuclear complexes. In each of the studied cases, one of the formed complexes is the kinetic product, and the other one is the thermodynamic product. The complexes which are thermodynamic products have been isolated in the pure form and characterized by means of high-resolution mass spectrometry, IR and NMR spectroscopy, and X-ray diffraction analysis. NMR study of the regioisomerization in a solution has revealed that the relative stability of the thermodynamic products in comparison with the kinetic ones is higher than for the corresponding regioisomers containing 1,3-thiazole or 1,3,4- thiadiazole fragment.

Assignment of the photoelectron spectrum of the nitrate anion NO3− and vibronic interactions in the nitrate free radical

The unpaired electron orbital of NO3 is of a2′ symmetry in the ground electronic state, and thus its motion about the symmetry axis of the molecule is free rotation. When a degenerate vibration is excited, however, the free azimuthal rotation of the unpaired electron is perturbed much by nuclear motions of the degenerate mode, as evidenced by high-resolution spectroscopic studies. Thus the ν4 fundamental state, for example, bears some characters of the B̃ excited electronic state through the Herzberg-Teller (H-T) interaction, and Neumark et al. explained anomalous ν4 progression in the photoelectron spectra of the NO3− anion by the H-T mechanism. However, the interaction parameter Neumark required was too large to reproduce the ν4 molecular parameters in the ground electronic state precisely determined by high-resolution IR spectroscopy. This discrepancy was resolved by the fact that the upper ν4 overtone/combination states of Neumark’s photoelectron transitions were primarily of vibrational in nature. The present study thus showed that NO3 bears both vibrational and H-T induced electronic characters in excited states of degenerate modes in the ground electronic state.

Synthesis of N-substituted imidazo[4,5-e]benzo[1,2-c;3,4-c’]difuroxans

N-Substituted imidazo[4,5-e]benzo[1,2-c;3,4-c’]difuroxans were synthesized by phase-transfer catalyzed alkylation of imidazo[4,5-e]benzo[1,2-c;3,4-c’]difuroxan salts with various alkylating agents. Acid hydrolysis of N-(ethoxycarbonylmethyl)imidazo[4,5-e]benzo-[1,2-c;3,4-c’]difuroxans gives the corresponding carboxylic acids. Structures of the synthesized compounds were confirmed by NMR spectroscopy, high resolution mass spectrometry, IR spectroscopy, and elemental anslysis.

Synthesis and Crystal Structure of Unexpected (1S,4R,5R,6S)-4-Cyano-2,2,6-trimethyl-3-azabicyclo[3.3.1]nonan-6-yl Acetate

The reaction of (–)-β-pinene with KCN under a mild bridged Ritter reaction gave (1S,5R,6S)-2,2,6-trimethyl-3-aza-bicyclo[3.3.1]non-3-en-6-yl acetate that subsequently reacted to provide an unexpected (1S,4R,5R,6S)-4-cyano-2,2,6-trimethyl-3-azabicyclo[3.3.1]nonane-6-yl acetate. The structure of the compound was determined by high-resolution mass spectrometry, and IR and NMR spectroscopy and confirmed by single crystal X-ray crystallography. The compound crystallises in the monoclinic P21 space group, with unit cell parameters a 8.6120 (17), b 7.4570 (15), c 11.189 (2) Å, and β 110.16 (3)°.

Cluster transformation of [Cu3(μ3-H)(μ3-BH4)((PPh2)2NH)3](BF4) to [Cu3(μ3-H)(μ2,μ1-S2CH)((PPh2)2NH)3](BF4) via reaction with CS2. X-ray structural characterisation and reactivity of cationic clusters explored by multistage mass spectrometry and computational studies.

The copper nanocluster [Cu3(μ3-H)(μ3-BH4)LPh3](BF4), 1a·BF4 (LPh = (PPh2)2NH = dppa), can potentially react with substrates at either the coordinated hydride or borohydride sites. Reaction of 1a·BF4 with CS2 has given rise to [Cu3(μ3-H)(μ2,μ1-S2CH)LPh3](BF4), (2a·BF4), which was structurally characterised using electrospray ionisation (ESI) with high-resolution mass spectrometry (HRMS), X-ray crystallography, NMR, IR and UV-Vis spectroscopy. The copper(i) atoms adopt a planar trinuclear Cu3 geometry coordinated on the bottom face by a μ3-hydride, on the top face by a μ2,μ1-dithioformate and surrounded by three bridging LPh ligands. Reaction of 1a·BF4 with elemental sulfur gives the known cluster [Cu4(LPh-H + 2S)3](BF4), (3·BF4), which was structurally characterised via X-ray crystallography. ESI-MS of 2a·BF4 produces [Cu3(H)(S2CH)LPh3]+ and its gas-phase ion chemistry was examined under multistage mass spectrometry conditions using collision-induced dissociation (CID). The primary product, [Cu3(H)(S2CH)LPh2]+, formed via ligand loss, undergoes further fragmentation via loss of thioformaldehyde to give [Cu3(S)LPh2]+. DFT calculations exploring rearrangement and fragmentation of the model system [Cu3(H)(S2CH)LMe2]+ (LMe = (PMe2)2NH = dmpa) provide a feasible mechanism. Thus, coupling of the coordinated hydride with the dithioformate ligands gives [Cu3(S2CH2)LMe2]+, which then undergoes CH2S extrusion via C-S bond cleavage to give [Cu3(S)LMe2]+.

Formation of Pd–Ag nanoparticles in supported catalysts based on the heterobimetallic complex PdAg2(OAc)4(HOAc)4

The formation of Pd–Ag nanoparticles deposited from the heterobimetallic acetate complex PdAg2(OAc)4(HOAc)4 on α-Al2O3, γ-Al2O3, and MgAl2O4 has been investigated by high-resolution trans-mission electron microscopy, temperature-programmed reduction, and IR spectroscopy of adsorbed CO. The reduction of PdAg2(OAc)4(HOAc)4 supported on γ-Al2O3 and MgAl2O4 takes place in two steps (at 15–245 and 290–550°C) and yields Pd–Ag particles whose average size is 6–7 nm. The reduction of the Pd–Ag catalyst supported on α-Al2O3 occurs in a much narrower temperature range (15–200°C) and yields larger nanoparticles (~10–20 nm). The formation of Pd–Ag alloy nanoparticles in all of the samples is demonstrated by IR spectroscopy of adsorbed CO, which indicates a marked weakening of the absorption band of the bridged form of adsorbed carbon monoxide and a >30-cm–1 bathochromic shift of the linear adsorbed CO band. IR spectroscopic data for PdAg2/α-Al2O3 suggest that Pd in this sample occurs as isolated atoms on the surface of bimetallic nanoparticles, as is indicated by the almost complete absence of bridged adsorbed CO bands and by a significant weakening of the Pd–CO bond relative to the same bond in the bimetallic samples based on γ-Al2O3 and MgAl2O4 and in the monometallic reference sample Pd/γ-Al2O3.

Synthesis, Structural Characterization, and Gas-Phase Unimolecular Reactivity of Bis(diphenylphosphino)amino Copper Hydride Nanoclusters [Cu3(X)(μ3-H)((PPh2)2NH)3](BF4), Where X = μ2-Cl and μ3-BH4.

An electrospray ionization mass spectrometry (ESI-MS) survey of the types of cationic copper clusters formed from an acetonitrile solution containing a 1:1:20 mixture of tetrakis(acetonitrile)copper(I) tetrafluoroborate [Cu(MeCN)4(BF4)], bis(diphenylphosphino)amine (dppa = (Ph2P)2NH = L), and NaBH4 revealed a major peak, which based on both the accurate masses and isotope distribution was assigned as [Cu3(BH4)(H)(L)3]+. This prompted synthetic efforts resulting in isolation of the dppa ligated trinuclear copper hydride nanoclusters, [Cu3(μ2-Cl)(μ3-H)(L)3](BF4) and [Cu3(μ3-BH4)(μ3-H)(L)3](BF4), which were subsequently structurally characterized using high resolution ESI-MS, X-ray crystallography, NMR, and IR spectroscopy. The X-ray structures reveal a common structural feature of the cation, in which the three copper(I) ions adopt a planar trinuclear Cu3 geometry coordinated on the bottom face by a μ3-hydride and surrounded by three dppa ligands. ESI-MS of [Cu3(μ2-Cl)(μ3-H)(L)3](BF4) and [Cu3(μ3-BH4)(μ3-H)(L)3](BF4) produces [Cu3(μ2-Cl)(μ3-H)(L)3]+ and [Cu3(μ3-BH4)(μ3-H)(L)3]+. The unimolecular gas-phase ion chemistry of these cations was examined under multistage tandem mass spectrometry conditions using collision-induced dissociation (CID). CID of both cations proceeds via ligand loss to give [Cu3(μ3-H)(X)(L)2]+, which is in competition with BH3 loss in the case of X = BH4. DFT calculations on the fragmentation of [Cu3(μ3-BH4)(μ3-H)(LMe)3]+ suggest that BH3 loss produces the hitherto elusive [Cu3(μ3-H)(μ2-H)(LMe)3]+, which undergoes further fragmentation via H2 loss. CID of the deuterium labeled cluster [Cu3(μ3-D)(μ3-BD4)(L)3]+ reveals that the competing losses of ligand and BD3 yield [Cu3(μ3-BD4)(μ3-D)(L)2]+ and [Cu3(D)2(L)3]+ as primary products, which subsequently fragment via further losses of BD3 or a ligand to give [Cu3(D)2(L)2]+. The coordinated hydrides in the latter ion are activated toward elimination of D2 to give [Cu3(L)2]+. Loss of HD and 2HD are minor channels, consistent with higher DFT predicted endothermicities to form [Cu3(D)(L)(L-H)]+ and [Cu3(L-H)2]+.

Swollen structure and electrostatic interactions of polyelectrolyte brush in aqueous solution

Abstract Surface grafting of polyelectrolytes on materials brings about various significant changes in surface properties such as wettability, adhesion, and friction, because of their excellent hydrophilicity and unique intermolecular interactions that depend on the ionic strength of the solution. This review paper describes the characterization of the swollen structure and electrostatic interaction of polyelectrolyte brushes in aqueous solution by use of optical tweezers and neutron reflectivity, in order to discuss the dissociation of ionic groups and charge distribution in the polyelectrolyte brush. In addition, the spreading and structure of water on the polyelectrolyte brush surface were characterized by high spatial resolution IR spectroscopy.

Ruthenium Carbonyl Complexes with Azole Heterocycles – Synthesis, X‐ray Diffraction Structures, DFT Calculations, Solution Behavior, and Antiproliferative Activity

The reactions of (H2azole)[trans-RuCl4(Hazole)2] [Hazole = 1H-pyrazole (Hpz), 1H-indazole (Hind), 1-methylindazole (1-Me-ind), or 1H-benzimidazole (Hbzim)] with 1:1 mixtures of 12 M HCl and formic acid resulted in the formation of trans-[RuCl4(CO)(Hazole)]– complexes, which were isolated and identified by X-ray diffraction as nBu4N[trans-RuCl4(CO)(Hpz)] (1a), nBu4N[trans-RuCl4(CO)(Hind)] (2a), [(Hind)2H][trans-RuCl4(CO)(Hind)] (2b), nBu4N[trans-RuCl4(CO)(1-Me-ind)] (3a), and nBu4N[trans-RuCl4(CO)(Hbzim)] (6a), whereas a prolonged reaction with 1H-benzimidazole afforded (nBu4N)2[trans-RuCl5(CO)] (7a). The reactions of [(DMSO)2H][trans-RuCl4(CO)(DMSO)] with different azole heterocycles in dichloromethane afforded five similar complexes, which were isolated as azolium salts (H2azole)[trans-RuCl4(CO)(Hazole)] [Hazole = 1H-indazole (2), 1-methylindazole (3), 2-methylindazole (4), 1H-imidazole (5), and 1H-benzimidazole (6)]. Complexes 2–6 were characterized by elemental analysis, high-resolution electrospray ionization (ESI) mass spectrometry, UV/Vis spectroscopy, and IR spectroscopy, and 3 was also characterized by X-ray diffraction. The pH of the solution was crucial for the stability of the obtained compound series. The interactions of 2–4 with the model proteins myoglobin and ubiquitin and the influence of the indazole tautomer identity on those processes were investigated by high-resolution mass spectrometry. The ruthenium(III) complexes interact with the proteins to form protein–RuII(CO) adducts, that is, metal reduction appears to be responsible for the release of the azole heterocycle but not CO. Moreover, the binding of the RuII(CO) unit to myoglobin reduces the observed global charge state of the adduct with respect to that of free myoglobin, which suggests that the Ru(CO) fragment can cross-link the protein backbone. Complexes 2–6 show low antiproliferative activity against the human cancer cell lines HeLa and MDA-MB-231 and the noncancerous cell line MRC-5, and this activity correlates with the low stability of complexes in aqueous media, especially at neutral or basic pH. The results are compared to previously reported data on ruthenium nitrosyl analogues and KP1019.

Experimental modeling of native carbon formation in a C–O–H fluid system

Integrated data are presented on structure–morphology features, as well as on the material and phase composition, of a fluid-produced carbonaceous substance (CS) formed under known thermodynamic conditions of the experiment (C–O–H system, 500–800°C, and 500–1000 atm). Solid products of the synthesis were examined by means of X-ray phase and thermal analyses, scanning electron microscopy combined with microprobe analysis, transmission electron microscopy, high-resolution Raman spectroscopy, IR spectroscopy, and CHN-analysis. The characteristics of the experimental CS may be applicable in genetic modeling of natural ore-bearing fluidal carbonaceous systems.

A new, low temperature long-pass cell for mid-infrared to terahertz spectroscopy and synchrotron radiation use

A new cell has been designed for accurate spectroscopic measurements in the 80-400 K temperature range with variable path lengths from 3 to more than 141 m. The spectral coverage at these temperatures ranges from the visible to less than 10 cm(-1), thanks to the use of diamond windows. The design of the cryostat and vacuum setups allows vibration-free operation. The equipment provides temperature homogeneity and pressure control to better than 2% over the 100-400 K and the 0.1-1000 mbar ranges. Remote-controlled opto-mechanical systems enable in situ adjustments as well as changes of the optical path length within half an hour, in order to optimize measurement time in an open user facility. It allows then to meet the specific requirements of high resolution measurements on the Far-Infrared AILES beamline at SOLEIL as well at the LISA facility, in Créteil, in the mid-IR. This new instrument opens up the way for many experiments in the field of high-resolution gas-phase IR spectroscopy, in particular, in quantitative spectroscopy for atmospheric applications: measurements of absorption line parameters (absolute intensities, cross sections, and pressure-induced widths) using Fourier transform spectroscopy. The design and performance of the equipment are briefly presented and illustrated on spectroscopic examples.