Highly Selective and Sensitive Near‐Infrared‐Fluorescent Probes for the Detection of Cellular Hydrogen Sulfide and the Imaging of H2S in Mice

Herein, we report the development of two fluorescent probes for the highly selective and sensitive detection of H₂S. The probes take advantage of a Cu^II? cyclen complex, which acts as a reaction center for H₂S and as a quencher of BODIPY (boron‐dipyrromethene)‐based fluorophores with emissions at 765 and 680 nm, respectively. These non‐fluorescent probes could only be turned on by the addition of H₂S, and not by other potentially interfering biomolecules, including reactive oxygen species, cysteine, and glutathione. In a chemical system, both probes detected H₂S with a detection limit of 80 nM . The probes were successfully used for the endogenous detection of H₂S in HEK 293 cells, for measuring the H₂S‐release activity of dietary organosulfides in MCF‐7 cells, and for the in vivo imaging of H₂S in mice.     

Ab initio studies of H2PXYH molecules (X,Y = O,S)

Ab initio molecular orbital theory is applied to the study of P? O and P? S bonding in the hypervalent phosphinic (H₂POOH), phosphinothioic (H₂POSH), and phosphinodithioic (H₂PSSH) acid molecules. Intramolecular proton exchange reactions are followed using the intrinsic reaction coordinate and Self-Consistent-Field energy localized orbitals. The P? O and PS bonds are characterized via force constants, phosphorus d orbital populations, and localized orbitals and are best described as either normal single bonds or dative bonds augmented by π back donation from the oxygen or sulfur lone pairs. The anions of these acids are also investigated, and they are found to contain only dative bonds to sulfur and oxygen.     

Colorimetric Carbonyl Sulfide (COS)/Hydrogen Sulfide (H2S) Donation from γ‐Ketothiocarbamate Donor Motifs

Hydrogen sulfide (H₂S) is a biologically active molecule that exhibits protective effects in a variety of physiological and pathological processes. Although several H₂S‐related biological effects have been discovered by using H₂S donors, knowing how much H₂S has been released from donors under different conditions remains challenging. Now, a series of γ‐ketothiocarbamate (γ‐KetoTCM) compounds that provide the first examples of colorimetric H₂S donors and enable direct quantification of H₂S release, were reported. These compounds are activated through a pH‐dependent deprotonation/β‐elimination sequence to release carbonyl sulfide (COS), which is quickly converted into H₂S by carbonic anhydrase. The p‐nitroaniline released upon donor activation provides an optical readout that correlates directly to COS/H₂S release, thus enabling colorimetric measurement of H₂S donation.     

Synthesis and characterization of phenoxarsin-10-yl 2-R2N-cyclopent-1-ene-1-carbodithioate (R = H,C2H5, cyclo-C6H11CH2) and the crystal and molecular structure of the 2-amino (R = H) derivative

Phenoxarsin-10-yl derivatives of 2-amino-cyclopent-1-ene-1-carbodithioic acid, (ACDA), and its N-alkyl derivativesO(C₆H₄)₂ AsS₂C—C₅H₆— NHR-2 (R = H, CH₂CH₃, CH₂C₆H₁₁,), have been prepared by reacting O(C₆H₄)₂AsCI with the corresponding ACDA 1,1-dithioic acid. The compounds were obtained by stirring stoichiometric amounts of the reagents in ethanol, over 24 h, at room temperature. The scale of the preparations were in the order of 2 mmol and the yields of the compounds ca 75%. The reactions were carried out in absolute ethanol. The compounds were characterized by IR, mass and NMR (¹H, ¹³C) spectroscopy. The molecular structure of O(C₆H₄)₂AsS₂C—C₅H₆—NH₂-2 was determined using X-ray diffractometry, achieving an R-value of 6.3%; this compound is monomeric and contains an asymmetric monometallic biconnective 1,1-dithiolato ligand [As—S(1) 2.272(2) å, As … S(2) 3.125(2) å]. An intramolecular hydrogen bond is established between one hydrogen atom of the NH₂ group and the sulfur [S(2)] atom involved in the secondary interaction to arsenic. The dihedral angle (150.3(3)°) of the phenoxarsine moiety is practically unaffected by substitution of chlorine on arsenic by the carbodithioato ligand.     

Complexes of N-Phosphorylated Thioureas RNHC(S)NHP(O)(OiPr)2 (R = 2-MeC6H4, 2,6-Me2C6H3, 2,4,6-Me3C6H2) With Nickel(II)

The reaction of O,O′-diisopropylphosphoric acid isothiocyanate (iPrO)₂P(O)NCS with 2-methylaniline 2-MeC₆H₄NH₂, 2,6-dimethylaniline 2,6-Me₂C₆H₃NH₂, or 2,4,6-trimethylaniline 2,4,6-Me₃C₆H₂NH₂ leads to the N-phosphorylated thioureas RNHC(S)NHP(O)(OiPr)₂ (R = 2-MeC₆H₄?, HL^I ; 2,6-Me₂C₆H₃?, HL^II ; 2,4,6-Me₃C₆H₂?, HL^III ). Reaction of the potassium salts of HL^{I –III} with Ni(II) in aqueous EtOH leads to [Ni(L^I–III-N,S)₂] ([NiL^I–III ₂ ]) chelate complexes. The compounds obtained were investigated by ¹H, ³¹P{¹H} NMR spectroscopy and microanalysis. The molecular structure of the thiourea HL^III was elucidated by single crystal X-ray diffraction analysis. Single crystal X-ray diffraction studies showed that HL^III forms both intra- and intermolecular hydrogen bonds, which in turn leads to the formation of polymeric chains. One of the intermolecular hydrogen bonds is of the type N?H…S. Moreover, the formation of intermolecular C?H…η⁶-phenyl interactions was established.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Crystal and molecular structure of (μ-p-CH3C6H4C2S) (μ-n-C3H7S)Fe2(CO)6Co2(CO)6

The crystal and molecular structure of the complex containing cobalt-carbon and iron-sulfur cluster cores, (μ-p-CH₃C₆H₄C₂S) (μ-n-C₃H₇S)Fe₂(CO)₆Co₂(CO)₆, has been determined by X-ray diffraction method. The crystals are triclinic, space group P&1bar;, with a — 9.139(2), b=9.610(1), c-17.183(2) Å, α = 84.36(1), β-89.45(1), γ=88.15(1)°, V-1501.0 ų; Z=2, D_c=1.74 g/cm³. R=0.072, Rw=0.081. The results of the structure determination show a cobalt-carbon cluster core formed through the reaction of (μ-p-CH₃C₆H₄C₂S)(μ-n-C₃H₇S)Fe₂(CO)₆ with Co₂(CO)₈. In the cobalt-carbon cluster core, the bond length of the original C≡C lengthened to 1.324 Å which is close to the typical value of carbon-carbon double bond. The groups connecting the carbons of the cluster core are in cis position and lie on the opposite side of cobalt atoms. In this complex, the conformation of —SC₃H₇ is e-type, while that of —SC₂C₆H₄CH₃ is a-type.     

Charge density studies on [(NO)Fe(S2C6H4)2][PPN] and [(NO)3Fe(S2C6H4)3] complexes

Charge density studies of chemical bonds for two iron complexes, [(NO)Fe(S,S-C₆H₄)₂] [PPN] (1), where PPN = N(Pph₃)₂ and Fe₃(NO)₃(S,S-C₆H₄)₃ (2) are investigated in terms of the topological properties at bond critical points based on the ‘atoms in molecule’ theory. The one electron reduction form (1R) of complex 1 and the one electron oxidation form (2O) of complex 2 are also included for comparison. The X-ray absorption spectroscopy of Fe K- and L_III,II-edges, as well as the N/S K-edge are applied to verify the illustration in the variation of the electronic structures. Based on the ρ_c, ?²ρ_c, and H_b values among the compound studied, Fe-S/N can be regarded as polarized covalent bond, and Fe-N bonds show stronger covalent character than that of the Fe–S bond, which is believed to be a highly polarized covalent bond.     

Energy transfer processes in reactions of He(23S) with triatomic molecules. II. H2O and H2S

The energy transfer reactions He(2³S) + H₂O and He(2³S) + H₂S were studied spectroscopically in the visible and ultraviolet ranges in a flowing afterglow apparatus. No primary triatomic ion emission was observed in this study. Only dissociative fragments were found to emit. In the He(2³S)/H₂O system intense OH(A²Σ⁺ → X²Π_i) emission bands and hydrogen Balmer series were observed while in the He(2³S)/H₂S system intense HS⁺(A³Π_i → X³ Σ^?), weak hydrogen Balmer series and some atomic sulfur lines were found. It is concluded that dissociative processes are competitive with Penning ionization in these energy transfer reactions with other possible reaction channels playing inferior roles. The post-ionization process of ion—electron recombination in the flowing afterglow dominates the emission results in the He(2³S)/H₂O system.     

Poly(ether urethane) and poly(ether urethane urea) membranes with high H2S/CH4 selectivity

The objective of this study was to synthesize rubbery polymers with a high H₂S/CH₄ selectivity for possible use as membrane materials for the separation of H₂S from ‘low-quality’ natural gas. Two poly(ether urethanes), designated hereafter PU1 and PU3, and two poly(ether urethane ureas), designated PU2 and PU4, were synthesized and cast in the form of ‘dense’ (homogeneous) membranes. PU1 and PU2 contained poly(propylene oxide) whereas PU3 and PU4 contained poly(ethylene oxide) as the polyether component. The permeability of these membranes to two ternary mixtures of CH₄, CO₂, and H₂S was measured at 35°C, and for a PU4 membrane also at 20°C, in the pressure range from 4 to 13.6 atm (4.05–13.78×10⁵ Pa). PU4 is a very promising membrane material for H₂S separation from mixtures with CH₄ and CO₂, having a H₂S/CH₄ selectivity greater than 100 at 20°C as well as a very high permeability to H₂S. Permeability measurements were also made with commercial PEBAX^TM membranes for comparison. The possibility of upgrading low-quality natural gas to US pipeline specifications for H₂S and CO₂ by means of membrane processes utilizing both highly H₂S-selective and CO₂-selective polymer membranes is discussed.     

一维链状配位聚合物{[Cu(H2bttc)(H2O)3]·3H2O}n的非等温反应动力学和晶体结构

为研究配位聚合物{[Cu(H₂bttc)(H₂O)₃]·3H₂O}_n(H₂bttc=1，2，4，5-benzenetetracarboxylate)的热分解机理和非等温反应动力学进行了DSC和TG-DTG热分析。由热分析结果和FTIR光谱推测了其热分解机理；将Kissinger法、Ozawa法、积分法和微分法得到的动力学参数进行比较确定了第一个失重过程最可能的动力学模型函数。配位聚合物的X射线单晶结构分析表明它由 [Cu(H₂bttc)(H₂O)₃]_n分子链组成，并有客体水分子通过分子间氢键附着在分子链上。这一结构特点与热分析结果相一致。还有一种氢键将分子链连接起来形成二维框架，这一框架在失去配位水和结晶水后到553 K开始分解。     

Chemistry of Energetically Activated Cumulenes—From Allene (H2CCCH2) to Hexapentaene (H2CCCCCCH2)

During the last decade, experimental and theoretical studies on the unimolecular decomposition of cumulenes (H₂C_nH₂) from propadiene (H₂CCCH₂) to hexapentaene (H₂CCCCCCH₂) have received considerable attention due to the importance of these carbon‐bearing molecules in combustion flames, chemical vapor deposition processes, atmospheric chemistry, and the chemistry of the interstellar medium. Cumulenes and their substituted counterparts also have significant technical potential as elements for molecular machines (nanomechanics), molecular wires (nano‐electronics), nonlinear optics, and molecular sensors. In this review, we present a systematic overview of the stability, formation, and unimolecular decomposition of chemically, photo‐chemically, and thermally activated small to medium‐sized cumulenes in extreme environments. By concentrating on reactions under gas phase thermal conditions (pyrolysis) and on molecular beam experiments conducted under single‐collision conditions (crossed beam and photodissociation studies), a comprehensive picture on the unimolecular decomposition dynamics of cumulenes transpires.     

Synthesis and structural characterization of cadmium(II) complexes with chelating keto-hydroxy compounds: The X-ray molecular structure of [Cd2(nq)4(H2O)4]·3H2O (nqH = 2-hydroxynaphthoquinone)

The reaction of cadmium(II) acetate dehydrate with the complexing agents tropolone (tropH), 2-hydroxynaphthoquinone (nqH), 1,2-dihydroxyanthraquinone (alizH₂), and 1,8-dihydroxyanthraquinone (chryzH₂), afforded the complexes [Cd(trop)₂] 1, [Cd₂(nq)₄(H₂O)₄]·3H₂O 2·3H₂O, [Cd(alizH)₂(H₂O)₃] 3, and [Cd(chryzH)₂(H₂O)₂] 4, respectively. The X-ray molecular structure of the dinuclear complex 2·3H₂O reveals that each cadmium(II) atom is seven-coordinated. The nature of water molecules (lattice or coordinated) was discerned by thermogravimetric studies. The ¹¹³Cd NMR spectra were discussed in light of the chemical exchange.     

Theoretical study of formation of ion pairs in (NH3��HCl)(H2O)6 and (NH3��HF)(H2O)6

We have performed theoretical studies on sixteen molecular cubes for both (NH₃·HCl)(H₂O)₆ and (NH₃·HF)(H₂O)₆. We use an empirical gauge, based upon the N?CH and H?CX bond lengths, to categorize the degree to which the cubes are neutral adduct or ion pair in character. On this basis, we describe all sixteen cubes of the former as highly ionized, but only five of the latter as greater than 85% ionic in character. Addition of one or two bridging water molecules to form (NH₃·HF)(H₂O)₇ or (NH₃·HF)(H₂O)₈ raises the percent ionic character to greater than 85% for these systems. The relative energy of the cubes can be categorized based on simple chemical principles. The computed vibrational frequency corresponding to the proton stretch in the N?CH?CF framework shows the highest degree of redshifting for systems near 50% ion-pair character. Molecular cubes close to neutral adduct or to ion-pair character show less redshifting of this vibrational motion.     

Crystal and molecular structure of bis(N,N-dipropyl-N′-diphenoxythiophosphoryl-thioureato) nickel(II) [(C6H5O)2P(S)NC(S)N(C3H7)2]2Ni

The Ni complex [C₆H₅O₂P(S)N(C₃H₇₂]₂Ni is monoclinic, space group P2₁/n with a = 8.890(3), b = 21.692(5), c = 11.670(4) Å, β = 108.35(5)°, V = 2136(1) ų, F(000) = 916, M_r = 534.01, Z = 2, D_m = 1.318, D_x = 1.358 Mg m^?3, graphite monochromatized MoKα ^? radiation, π = 0.7107 Å, μ = 0.76 mm^?1, T = 293 K. The structure was solved by a heavy atom method and refined to R = 0.044 for 3095 independent reflexions. The Ni atom lies in the centre of symmetry and is coordinated by four S atoms of the two molecules of the ligand in a planar arrangement. Ni? S bond lengths are 2.205 and 2.226 Å resp., the angles S? Ni? S are 97.65 and 82.35° resp.     

Synthese und Kristallstruktur von K2(HSO4)(H2PO4), K4(HSO4)3(H2PO4) und Na(HSO4)(H3PO4)

Synthesis and Crystal Structure of K₂(HSO₄)(H₂PO₄), K₄(HSO₄)₃(H₂PO₄), and Na(HSO₄)(H₃PO₄) Mixed hydrogen sulfate phosphates K₂(HSO₄)(H₂PO₄), K₄(HSO₄)₃(H₂PO₄) and Na(HSO₄)(H₃PO₄) were synthesized and characterized by X‐ray single crystal analysis. In case of K₂(HSO₄)(H₂PO₄) neutron powder diffraction was used additionally. For this compound an unknown supercell was found. According to X‐ray crystal structure analysis, the compounds have the following crystal data: K₂(HSO₄)(H₂PO₄) (T = 298 K), monoclinic, space group P 2₁/c, a = 11.150(4) Å, b = 7.371(2) Å, c = 9.436(3) Å, β = 92.29(3)°, V = 774.9(4) ų, Z = 4, R₁ = 0.039; K₄(HSO₄)₃(H₂PO₄) (T = 298 K), triclinic, space group P 1, a = 7.217(8) Å, b = 7.521(9) Å, c = 7.574(8) Å, α = 71.52(1)°, β = 88.28(1)°, γ = 86.20(1)°, V = 389.1(8)ų, Z = 1, R₁ = 0.031; Na(HSO₄)(H₃PO₄) (T = 298 K), monoclinic, space group P 2₁, a = 5.449(1) Å, b = 6.832(1) Å, c = 8.718(2) Å, β = 95.88(3)°, V = 322.8(1) ų, Z = 2, R₁ = 0,032. The metal atoms are coordinated by 8 or 9 oxygen atoms. The structure of K₂(HSO₄)(H₂PO₄) is characterized by hydrogen bonded chains of mixed H_nS/PO₄^– tetrahedra. In the structure of K₄(HSO₄)₃(H₂PO₄), there are dimers of H_nS/PO₄^– tetrahedra, which are further connected to chains. Additional HSO₄^– tetrahedra are linked to these chains. In the structure of Na(HSO₄)(H₃PO₄) the HSO₄^– tetrahedra and H₃PO₄ molecules form layers by hydrogen bonds.     

Novel Cyclometallated Complexes Derived From a Halogenated Thiosemicarbazone. Crystal and Molecular Structures of 2‐FC6H4C(Me)=NN(H)C(=S)NHPh and [(Pd{2‐FC6H3C(Me)=NN=C(S)NHPh})2(μ‐PPh2(CH2)2PPh2)]

Treatment of the thiosemicarbazone 2‐FC₆H₄C(Me)=NN(H)C(=S)NHPh, a , with palladium(II) acetate in acetic acid, or with lithium tetrachloropalladate(II) in methanol, gave the tetranuclear cyclometallated complex [Pd{2‐FC₆H₃C(Me)=NN=C(S)NHPh}]₄ (1a) . Reaction of 1a with the diphosphines Ph₂P(CH₂)₂PPh₂ (dppe), Ph₂PCH=CHPPh₂ (trans‐dpe) Ph₂P(CH₂)₃Ph₂ (dppp) or Ph₂P(CH₂)₄Ph₂ (dppb) in a 1:2 molar ratio gave the dinuclear cyclometallated complexes [(Pd{2‐FC₆H₃C(Me)=NN=C(S)NHPh})₂(μ‐Ph₂P(CH₂)_nPPh₂)], (n = 2, 2a ; 3, 4a ; 4, 5a ) and [(Pd{2‐FC₆H₃C(Me)=NN=C(S)NHPh})₂(μ‐Ph₂PCH=CHPPh₂)], ( 3a ). The X‐ray crystal structure of ligand a and of complex 2a are described. The structure of complex 2a shows the palladium atom is bonded to four different donor atoms: C, N, S and P.     

Electron energy loss spectroscopy (EELS) of H2O,H2S,H2Se and H2Te

Electronic excitation in H₂O, H₂S, H₂Se and H₂Te molecules has been studied by the EELS technique. Spectra of H₂S and H₂Se are remarkably similar with the 1b₁-nd transition most intense. The intensity of the first transition 1b₁-nsa₁ decreases through H₂O to H₂Se and this transition is absent in H₂Te. Transitions observed by EELS have been compared with optical absorption studies. A correlation diagram of the occupied and the excited states has been provided for these four molecules by making use of UVPES and EELS.     

Two saccharinate complexes: [Mn(phen)2(sac)(H2O)]+·sac– and [Co(bipy)2(sac)(H2O)]+·sac–

The title saccharinate complexes, aqua[1,2‐benzisothiazol‐3(2H)‐onato 1,1‐dioxide‐N]bis(1,10‐phenanthroline‐N,N′)man­ganese(II) 1,2‐benz­isothia­zol‐3(2H)‐onate 1,1‐dioxide,[Mn(C₇H₄NO₃S)(C₁₂H₈N₂)₂(H₂O)](C₇H₄NO₃S), and aqua[1,2‐benz­iso­thiazol‐3(2H)‐onato 1,1‐dioxide‐N]­bis­(2,2′‐bi­pyri­dine‐N,N′)­cobalt(II) 1,2‐benz­iso­thia­zol‐3(2H)‐onate 1,1‐di­oxide, [Co­(C₇H₄NO₃S)­(C₁₀H₈N₂)₂­(H₂O)]­(C₇H₄NO₃S), have been prepared and their crystal structures determined at 150 K. The structure of the manganese complex consists of repeated alternating [Mn(phen)₂(sac)(H₂O)]⁺ cations and non‐coordinated saccharinate anions. The water molecule, bound to manganese as part of a slightly distorted octahedral arrangement, is hydrogen bonded to an O atom of the SO₂ group in the saccharinate counter‐ion. In contrast, the cobalt complex has one pseudo‐octahedral [Co(bipy)₂(sac)(H₂O)]⁺ cation, with the cobalt‐bound water molecule hydrogen bonded to the N atom of the accompanying free saccharinate anion.     

A pseudopotential study of the hydrogen bond in H2O·H2S,H2S·H2S and H2O·H2Se systems

Intermolecular potential energy curves for the hydrogen bonded systems H₂O·H₂S, H₂O·H₂Se and H₂S·H₂S were calculated with nonempirical pseudopotentials using optimized-in-molecules basis sets augmented by polarization functions. The H₂O·H₂O interaction energy curve has been also considered as a test case. The present results for H₂O·H₂S and H₂S·H₂S indicate much weaker intermolecular interactions than those found in previous ab initio calculations. The H₂O·H₂Se interaction was found to be quite similar to H₂O·H₂S.This work was partly supported by the Polish Academy of Sciences within the Project PAN-09, 7.1.1.1On leave from Quantum Chemistry Laboratory, Dept. of Chemistry, University of Warsaw, Pasteura 1, 02-093. Warsaw, Poland     

H2S splitting on Cu(110): Insight from combined periodic density functional theory calculations and microkinetic simulation

Practical copper (Cu)‐based catalysts for the water–gas shift (WGS) reaction was long believed to expose a large proportion of Cu(110) planes. In this work, as an important first step toward addressing sulfur poisoning of these catalysts, the detailed mechanism for the splitting of hydrogen sulfide (H₂S) on the open Cu(110) facet has been investigated in the framework of periodic, self‐consistent density functional theory (DFT‐GGA). The microkinetic model based on the first‐principles calculations has also been developed to quantitatively evaluate the two considered decomposition routes for yielding surface atomic sulfur (S*): (1) H₂S → H₂S* → SH* → S* and (2) 2H₂S → 2H₂S* → 2SH* → S* + H₂S* → S* + H₂S. The first pathway proceeding through unimolecular SH* dissociation was identified to be feasible, whereas the second pathway involving bimolecular SH* disproportionation made no contribution to S* formation. The molecular adsorption of H₂S is the slowest elementary step of its full decomposition, being related with the large entropy term of the gas‐phase reactant under realistic reaction conditions. A comparison of thermodynamic and kinetic reactivity between the substrate and the close‐packed Cu(111) surface further shows that a loosely packed facet can promote the S* formation from H₂S on Cu, thus revealing that the reaction process is structure sensitive. The present DFT and microkinetic modeling results provide a reasonably complete picture for the chemistry of H₂S on the Cu(110) surface, which is a necessary basis for the design of new sulfur‐tolerant WGS catalysts. © 2013 Wiley Periodicals, Inc.