New cyclopeptides from Trichoderma polysporum (Link ex Pers.) Rifai: cyclosporins B, D and E (author's transl)

New Cyclopeptides from Trichoderma polysporum (LINK EX PERS .) RIFAI : Cyclosporins B, D and E Cyclosporins represent a new group of biologically active metabolites produced by Trichoderma polysporum (LINK EX PERS .) RIFAI and other fungi imperfecti. The structures of the main components, cyclosporins A ( 1 ) and C( 3 ) have been determined as neutral cyclic oligopeptides composed of 11 amino acids, among them a new C₉-amino acid [2–4]. In addition, three minor metabolites, cyclosporins B, D and E, have now been isolated and characterized. Chemical investigation, spectroscopic evidence and X-ray analysis led to the structural formulae of cyclosporins B (2) and D (4) . Both compounds have the same sequence of amino acids as cyclosporin A (1) , with the exception of L -α-aminobutyric acid, replaced in cyclosporin B (2) by L -alanine and in cyclosporin D (4) by L -valine, respectively. Cyclosporins undergo a characteristic intramolecular N,O-acyl migration to furnish the corresponding basic isocompounds. The antifungal activities of cyclosporins are reported.     

Sequencing of cyclosporins by fast atom bombardment and linked-scan mass spectrometry

The mass spectrometric sequence determination of amino acid residues in cyclosporins using fast atom bombardment, collisionally activated dissociations in the first field-free region and linked B/E scan is described. The general fragmentation scheme was derived from the spectra of cyclosporins A, B, C, D, F, G, L and [DH-MeBmt¹]CS. The main fragmentation pathways start by primary splitting between amino acids 2–3, 1–11 and 5–6. The corresponding N-terminal b-type ions are common fragment types in the mass spectra. The 1–11 splitting can be enhanced by the introduction of a lactone group into the peptide ring by conversion of cyclosporins into isocyclosporins. The fragmentation scheme was used for amino acid sequence determination in four new natural cyclosporins, [MeLeu¹]CS, [Leu⁴]CS, [Ile⁴]CS and [Leu⁵]CS.     

Synthesis of Cyclosporine. I. Synthesis of enantiomerically pure (2S,3R,4R,6E)-3-hydroxy -4-methyl-2-methylamino-6-octenoic acid starting from tartaric acid

Starting from R,R-(+)-tartaric acid, the synthesis of (2S,3R,4R6E)-3-hydroxy -4-methyl-2-methylamino-6-octenoic acid in 24 steps is reported. This novel amino acid is found in the cyclic undecapeptide cyclosporin A, isolated from the fungal strain Tolypocladium inflatum GAMS . Its stereospecific synthesis allowed, for the first time, the isolation and characterization of the new amino acid previously reported as the ‘C-9-amino acid’ [1].     

Piezomodulated reflection spectra of anthracene single crystals

The first piezomodulation spectra of Frenkel exciton states of a molecular crystal are reported for the (001) face of anthracene from 25 000 cm^?1 to 45 000 cm^?1. The piezoreflection spectra show structure at 300 K which may be correlated with that observed in the specular reflection spectra at 2 K. Davydov splittings at 300 K of 165 cm^?1 for 0–0 and 50 cm^?1 for 0–1 are observed.     

Polysulfonylamine. CLXXVIII Onium‐Salze des Benzol‐1,2‐di(sulfonyl)amins (HZ): Eine zweite Kristallform des Ammonium‐Salzes NH4Z·H2O und Kristallstruktur des Bis(triphenylphosphoranyliden)ammonium‐Salzes [Ph3PNPPh3]Z

Polysulfonylamines. CLXXVIII. Onium Salts of Benzene‐1,2‐di(sulfonyl)amine (HZ): A Second Crystal Form of the Ammonium Salt NH₄Z·H₂O and Crystal Structure of the Bis(triphenylphosphoranylidene)ammonium Salt [Ph₃PNPPh₃]Z A dimorphic form of NH₄Z·H₂O, where Z^? is N‐deprotonated ortho‐benzenedisulfonimide, has been obtained and structurally characterized (previously known form 1A : monoclinic, P2₁/c, Z′ = 1; new polymorph 1B : monoclinic, P2₁/n, Z′ = 1). Both structures are dominated by an abundance of classical hydrogen bonds N⁺–H/O–H···O=S/OH₂, whereby the anionic N^? function does not act as an acceptor. The major difference between the dimorphs arises from the topology of the hydrogen bond network, which is two‐dimensional in 1A , leading to a packing of discrete lamellar layers, but three‐dimensional in 1B . Moreover, the latter network is reinforced by a set of weak C–H··O/N hydrogen bonds, whereas the layered structure of 1A displays only one independent C–H···O bond, providing a link between adjacent layers. The compound [Ph₃PNPPh₃]Z ( 2 , monoclinic, P2₁/c, Z′ = 1) is the first structurally authenticated example of an ionic Z^? derivative in which the cation contains neither metal bonding sites nor strong hydrogen bond donors. This structure exhibits columns of anions, surrounded by four parallel columns of cations, giving a square array. The large cations are associated into a three‐dimensional framework via weak C–H···C(π) interactions and an offset face‐to‐face phenyl interaction, while the anions occupy tunnels in this framework and are extensively bonded to the surrounding cations by C–H···O/N^? hydrogen bonds and C–H···C(π) interactions.     

Strukturelle und spektroskopische Charakterisierung sechsfach koordinierter Vanadium(V)-Komplexe: Ein Strukturmodell für das aktive Zentrum Vanadium-abhängiger Haloperoxidasen

Structural and Spectroscopic Characterization of Six-Coordinate Vanadium(V) Complexes: A Structural Model for the Active Site of Vanadium-Dependent Haloperoxidases A series of vanadium(V) complexes has been synthesized from ammonium metavanadate and trivalent, pentadentate Schiff base ligands. These aliphatic as well as aromatic hydroxyl groups containing ligands are stabilizing the VO³⁺ unit. The complexes 1–5 are characterized by ¹H-, ¹³C- and ⁵¹V-NMR, virbrational (IR, Raman and resonance Raman) and electronic spectroscopy as well as EHMO calculations. The X-ray crystal structure analysis of 1 (monoclinic space group P2₁/n: a = 1 073.3(2); b = 1 201.1(3); c = 1 165.7(3) pm; β = 101.89(2)°; Z = 4) shows that the vanadium(V) center has a distorded octahedral environment. The LMCT transition of the complexes 1–5 in the electronic spectra has been observed at comparatively high energies (21.8 ? 25.8 × 10³ cm^?1) and are assigned based on resonance Raman spectra and EHMO calculations. The implications of the observed physical properties of the complexes 1–5 to the structural model proposed for the active site of vanadat(V)-dependent haloperoxidases are discussed.     

Fast atom bombardment mass spectrometry of alkali metal fluorides and chlorides; a comparison of the solid salt and glycerol matrix spectra

The Fast Atom Bombardment (FAB) mass spectra of the alkali metal chlorides (Na, K, Cs) and fluorides (Na, K, Rb, Cs) were obtained from solids and a glycerol matrix, using a fast atom bombardment source. From solids the fluorides exhibited an ion abundance enhancement of the well-known [M(MF)₄]⁺ cluster, which decreased with increasing cation size. A gradual decrease in the n=4 enhancement was observed as the salt was diluted with glycerol. In the chlorides only sodium chloride showed the n=4 relative enhancement. The mass spectra of the salts from a glycerol matrix at molar ratios of 1:1 to 1:10 showed that the spectra of the 1:1 solutions were similar to those from the solids, while glycerol adducts were found to increase with increasing glycerol concentration. A [M(MX)_n(gly)]⁺ species that featured successive losses of HX was observed. It has not been established whether HX losses take place in solution, in the surface/vacuum interface and/or whether gas phase reactions might be responsible for the observation of the [M(MX)_n(gly)–y HX]^? species in the mass spectra of the MX/glycerol system.     

Synthesis and Properties of a New Two—Photon—absorbed Material DMAEAS

IntroductionSubstitutedstilbeneshavesignificantpotentialapplica tionssuchasfluorescencemicroscopy ,two photonphotody namictherapy ,opticalpowerlimiting ,three dimensionalstorage,andthree dimensionalmicrofabrication .1 4 Thesedyeshavestrongtendencyofintra molecularchargetransferundertheexcitedstate.Asaresult,theyusuallyexhibitlargetwo photonabsorption (TPA) ,inthemeanwhileemitstrongup convertedfluorescence .Ontheotherhand ,theirsolutionsgenerallydisplaylineartransmissionof >90 %atwavelengthof…     

Darstellung,spektroskopische Charakterisierung und Kristallstrukturen von [(C5H5N)2CH2][PtCl5(SCN)] und cis-[(C5H5N)2CH2][PtCl4(SCN)2]

Preparation, Spectroscopic Characterization, and Crystal Structures of [(C₅H₅N)₂CH₂][PtCl₅(SCN)] and cis -[(C₅H₅N)₂CH₂][PtCl₄(SCN)₂] By treatment of [PtCl₆]^2– with SCN^– in aqueous solution a mixture of chlorothiocyanatoplatinates(IV) is formed, from which [PtCl₅(SCN)]^2– and cis-[PtCl₄(SCN)₂]^2– have been separated by ion exchange chromatography on diethylaminoethyl cellulose. X-Ray structure determinations on single crystals of [(C₅H₅N)₂CH₂][PtCl₅(SCN)] ( 1 ) (tetragonal, space group P 4₃, a = 7.687(1), c = 29.698(4), Z = 4) and cis-[(C₅H₅N)₂CH₂][PtCl₄(SCN)₂] ( 2 ) (monoclinic, space group P 2₁/n, a = 11.2467(9), b = 15.0445(10), c = 11.3179(13), β = 92.840(9)°, Z = 4) show, that the thiocyanate groups are coordinated via S atoms with average Pt–S distances of 2.339 Å and Pt–S–C angles of 104.7° up to 107.1°. Using the molecular parameters of the X-ray determinations the low temperature (10 K) IR and Raman spectra have been assigned by normal coordinate analyses. The valence force constants of the S–Pt–Cl˙ axes are f_d(PtS) = 1.81 ( 1 ) and 1.87 ( 2 ), f_d(PtCl ^× ) = 1.77 ( 1 ) and 1.81 ( 2 ), of the Cl–Pt–Cl axes are f_d(PtCl) = 1.93 ( 1 ) and 1.90 mdyn/Å ( 2 ). The ¹⁹⁵Pt NMR spectra from dichlormethane solutions exhibit each one sharp signal at 3975.6 ( 1 ) and 3231.6 ppm ( 2 ), respectively.     

Conformational Studies of a Six-Membered Phostone

Abstract

Although 1,3,2-dioxaphosphorinanes generally assume chair conformations,¹ there are examples in which the ring adopts the boat or twist-boat form.¹ Recent studies on the synthesis, stereochemistry, and reactivity of 2-alkoxy-2-oxo-1,2-oxaphosphorinanes (phostones) have revealed both cis and trans isomers of 3-(diphenylhydroxymethyl)-2-ethoxy-2-oxo-1,2-axaphosphorinane² to assume a chair conformation in the solid state. In the present work, the conformational properties of cis and trans-3-methoxycarbonyl-2-methoxy-2-oxo-1,2-oxaphosphorinanes were investigated by X-ray analysis, variable temperature ³¹P, ¹H and ¹H{³¹P} NMR spectroscopy, molecular mechanics, and semiempirical calculations. The X-ray crystal structure of the trans isomer revealed a chair dormation with equatorial phosphoryl and carbomethoxy groups. No changes were observed in the ³¹P NMR spectra of either isomer in the temperature range of 183–333 K. A complete set of vicinal J_HH coupling constants was extracted from the ¹H{³¹P} spectra of each isomer taken at five temperatures over the range of 213–293 K and refined by simulation of the spectra. The best-fit analysis of this data using a generalized Karplus equation³ revealed that the conformation of the trans isomer in solution was close to that found in the solid state. This conformation corresponded to the global energy minimum calculated by both molecular mechanics and PM3 semiempirical method. A substantial contribution from an inverted chair conformation of the cis isomer had to be assumed to achieve a reasonable fit of the coupling constants calculated from the generalized Karplus equation.     

Synthesis and Nonlinear Optical Characterization of a New Twophoton Absorbing Organic Dye：DMAHAS

IntroductionThepotentialforuseoftwo photonabsorbingmoleculesinapplicationsrangingfromopticallimiting1 3tothreedimensional (3D)fluorescencemicroscopy4 and 3Dmicrofabricationandopticaldatastorage5,6 hasstimulatedresearchonthedesign ,synthesis ,andcharacterizationofnewmoleculeswithlargetwo photonabsorptivities .7,8Thetwo photonabsorption (2PA)processconsideredherein volvesthesimultaneousabsorptionoftwophotons ,eitherdegeneratingornondegenerating ,atwavelengthswellbe yondthelinearabsorptionspectr…     

Reinterpretation of Dynamic Vibrational Spectroscopy to Determine the Molecular Structure and Dynamics of Ferrocene

Molecular distortion of dynamic molecules gives a clear signature in the vibrational spectra, which can be modeled to give estimates of the energy barrier and the sensitivity of the frequencies of the vibrational modes to the reaction coordinate. The reaction coordinate method (RCM) utilizes ab initio‐calculated spectra of the molecule in its ground and transition states together with their relative energies to predict the temperature dependence of the vibrational spectra. DFT‐calculated spectra of the eclipsed (D_5h) and staggered (D_5d) forms of ferrocene (Fc), and its deuterated analogue, within RCM explain the IR spectra of Fc in gas (350 K), solution (300 K), solid solution (7–300 K), and solid (7–300 K) states. In each case the D_5h rotamer is lowest in energy but with the barrier to interconversion between rotamers higher for solution‐phase samples (ca. 6 kJ mol^?1) than for the gas‐phase species (1–3 kJ mol^?1). The generality of the approach is demonstrated with application to tricarbonyl(η⁴‐norbornadiene)iron(0), Fe(NBD)(CO)₃. The temperature‐dependent coalescence of the ν(CO) bands of Fe(NBD)(CO)₃ is well explained by the RCM without recourse to NMR‐like rapid exchange. The RCM establishes a clear link between the calculated ground and transition states of dynamic molecules and the temperature‐dependence of their vibrational spectra.     

BATHOPRODUCTS and CONFORMERS OF ALL-trans-AND 13-ds BACTERIORHODOPSIN AT 90 K*

Abstract– At 90 K the photoproduct of the primary light reaction of (rani-bacteriorhodopsin, the bathoproduct K¹ consists of a mixture of at least three spectrally different species, K¹_I, K¹_II, and K¹_III having maxima in the difference absorption spectra at 645, 635 and 625 nm, respectively. The bathoproducts differ in their long wavelength absorption bands and in their rate constants for photo-conversion to trans-bacteriorhodopsin under far red light irradiation (λ > 720 nm). The bathoproducts are formed from different precursors–conformers of trans-bacteriorhodopsin, which are stable at 90 K, but are in equilibrium with each other at 213 K. We suggest that the bathoproducts may initiate parallel conversion cycles of trans-bacteriorhodopsin at low temperatures. The primary photoreaction of 13-cis-bacteriorhodopsin also yields three bathoproducts, K^c_I, K^c_II and K^c_III having maxima in the difference absorption spectra at 615, 605 and 595 nm, respectively.     

Synthesis and Stereochemistry of New N-Substituted Cytisine Derivatives

A series of new N-substituted cytisine derivatives was synthesized. The ¹ H and ¹³ C NMR spectra of certain compounds exhibit a doubled set of signals. This is explained by formation of diastereomeric pairs in compounds containing an asymmetric center in the substituents. The signal splitting in -COHC=CHCO ₂ H and HC=O (formyl) derivatives is explained by the existence of Z and E invertomers. Their stereochemical features are discussed. Amide conjugation is confirmed by temperature experiments.     

Regioselective synthesis,structure and behavior in solutions of novel phosphorylated thiazolidin‐4‐ones

Regioselective syntheses of novel 2‐(phosphoryl)methylidenethiazolidine‐4‐ones 3a–c, 5 by the condensation of phosphoryl acetic acid thioamides 2a–c or substituted thioanilide 4 with dimethyl acetylenedicarboxylate are described. N³‐unsubstituted thiazolidine‐4‐ones 3a–c were obtained as E,Z‐isomers, while N³‐phenyl substituted heterocycle 5 was formed as Z,Z‐isomer. The structures of thiazolidin‐4‐ones 3a ‐E,Z and 5 ‐Z,Z are characterized by crystal structure determination. According to B3Pw91/6‐31G* calculations, the isomers observed in crystals are thermodynamically preferable. In solutions, phosphorylated thiazolidines undergo isomerization (relative to C² carbon atom of the heterocycle) proceeded by either imine–enamine (N³‐unsubstituted compounds 3a–c ) or push–pull mechanisms (N³‐substituted compound 5 ). © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:159–222, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20084     

Reversible Immobilization of Peptides: Surface Modification and In Situ Detection by Attenuated Total Reflection FTIR Spectroscopy

A generic method is described for the reversible immobilization of polyhistidine‐bearing polypeptides and proteins on attenuated total reflecting (ATR) sensor surfaces for the detection of biomolecular interactions by FTIR spectroscopy. Nitrilotriacetic acid (NTA) groups are covalently attached to self‐assembled monolayers of either thioalkanes on gold films or mercaptosilanes on silicon dioxide films deposited on germanium internal reflection elements. Complex formation between Ni²⁺ ions and NTA groups activates the ATR sensor surface for the selective binding of polyhistidine sequences. This approach not only allows a stable and reversible immobilization of histidine‐tagged peptides (His–peptides) but also simultaneously allows the direct in situ quantification of surface‐adsorbed molecules from their specific FTIR spectral bands. The surface concentrations of both NTA and His–peptide on silanized surfaces were determined to be 1.1 and 0.4 molecules nm^?2, respectively, which means that the surface is densely covered. A comparison of experimental FTIR spectra with simulated spectra reveals a surface‐enhancement effect of one order of magnitude for the gold surfaces. With the presented sensor surfaces, new ways are opened up to investigate, in situ and with high sensitivity and reproducibility, protein–ligand, protein–protein, protein–DNA interactions, and DNA hybridization by ATR–FTIR spectroscopy.     

14‐Membered Cyclopeptides from Paliurus ramosissimus and P. hemsleyanus

Six 14‐membered cyclopeptide alkaloids, i.e., ramosines A–C, mucronine J, and lotusines A and D, were isolated from the roots of Paliurus ramosissimus, and an additional four, hemsines A–D, from the roots of P. hemsleyanus. Among these, ramosines A–C ( 1, 5 , and 6 , resp.) and hemsines A and B ( 7 and 8 , resp.) are new bases of the amphibine‐B type, and hemsines C and D ( 9 and 10 , resp.) are new integerrine‐type alkaloids. Additionally, ramosine C ( 6 ) represents the first 14‐membered cyclopeptide alkaloid possessing a substitution (? OH) at C(13′). Their structural elucidations were based on spectral analysis and molecular‐modeling studies. Pronounced solvent effects in the ¹H‐ and ¹³C‐NMR spectra of these two types of alkaloids were observed.     

Pentastrontium Tris[tetraoxovanadate(V)] catena‐Monoxocuprate(I), Sr5(VO4)3(CuO) – An Apatite Derivative with Inserted Linear 1Ë[CuO]1– Chains

Sr₅(VO₄)₃(CuO) was prepared via solid state reactions from mixed powders of the metal oxides or carbonates in corundum crucibles in air (1173–1740 K). The compound is transparent and stable in air. The color changes with the preparation temperature from light gray (1173 K) to gray (1740 K). The crystal structure (space group P6₃/m, No. 176; Z = 2; a = 10.126 Å, c = 7.415 Å) is a derivative of the apatite Ca₅(PO₄)₃OH, and is characterized by isolated [VO₄]^3– anions (d(V–O) = 1.710 Å) and infinite linear ^1∞[CuO]^1– chains (d(Cu–O) = 1.854 Å) inserted in the channels parallel to the hexagonal axis. The compound prepared at 1740 K contains vacancies at the copper and oxygen positions of the linear chains (about 10% and 5%, respectively).     

Darstellung,Kristallstruktur und Eigenschaften des Kupfer(II)‐Indium(III)‐Orthophosphats Cu3In2[PO4]4

Contributions on Crystal Chemistry and Thermal Behaviour of Anhydrous Phosphates. XXIV. Preparation, Crystal Structure, and Properties of Copper(II) Indium(III) Orthophosphate Cu₃In₂[PO₄]₄ Crystals of Cu₃In₂[PO₄]₄ were grown by chemical vapour transport (temperature gradient 1273 K → 1173 K) using chlorine as transport agent. The mixed metal phosphate forms a new structure type (P2₁/c, Z = 2, a = 8.9067(6), b = 8.8271(5), c = 7.8815(5) Å, β = 108.393(5)°, 13 atoms in asymmetric unit, 2549 unique reflections with F_o > 4σ, 116 variables, R(F²) = 0.065). The crystal structure shows a hexagonal closest packing of [PO₄]^3– tetrahedra. Close‐packed layers parallel (1 0 –1) are stacked according to the sequence A, B, A′, B′, A. The octahedral interstices in this packing are completely occupied by two In³⁺, one (Cu1)²⁺ and a “dumb bell” (Cu2)₂⁴⁺. In the latter case four of the six phosphate groups that belong to this octahedral void act as bi‐dentate ligands, thus forming dimers [(Cu2)₂O₁₀] with d_Cu–Cu = 3.032 Å. Cu₃In₂[PO₄]₄ is paramagnetic (μ_eff = 1.89 μ_B, θ_P = –16.9 K). The infrared and UV/Vis reflectance spectra are reported. The observed d‐electron levels of the Cu²⁺ cations agree well with those obtained from angular overlap calculations.     

Stable Single‐Molecule Lines of Terrylene in Polycrystalline para‐Dichlorobenzene at 1.5 K

The spectroscopic properties of single terrylene (Tr) molecules are studied in a polycrystalline matrix of para‐dichlorobenzene (p‐DCB) at 1.5 K. Samples grown in a glass capillary show a very strong site at 597 nm, which is redshifted by more than 700 cm^?1 from the observed transition energy for Tr in p‐DCB prepared as a film on a coverslip (572 nm). Each of these two sites is characterized by measuring their single‐molecule spectroscopic parameters at 1.5 K. Lifetime‐limited linewidths of 45±5 MHz are found for both sites. Fluorescence detection rates reach 8×10⁴ count s^?1 at saturation. The spectral trails of the majority of single molecules show no spectral jumps, indicating an absence of interacting two‐level systems; however, the small distribution of linewidths may indicate weak interactions with low‐frequency modes. Frequency jumps are observed for 10 % of the molecules. The complete emission spectra from two different single molecules at the center of each of the two sites is presented. Debye–Waller factors of α_DW=0.33±0.05 for the normal site (572 nm) and α_DW=0.30±0.05 for the red site (597 nm) are reported. This new host–guest system provides a quick and easy way to obtain lifetime‐limited single‐molecule lines.