Marilines A-C: novel phthalimidines from the sponge-derived fungus Stachylidium sp

A marine-derived fungus of the genus Stachylidium was isolated from the sponge Callyspongia cf. C. flammea. Chemical investigation of the bioactive fungal extract led to the isolation of the novel phthalimidine derivatives marilines A(1) (1a), A(2) (1b), B (2), and C (3). The absolute configurations of the enantiomeric compounds 1a and 1b were assigned by a combination of experimental circular dichroism (CD) investigations and quantum chemical CD calculations. The skeleton of marilines is most unusual, and its biosynthesis is suggested to require uncommon biochemical reactions in fungal secondary metabolism. Both enantiomers, marilines A(1) (1a) and A(2) (1b), inhibited human leukocyte elastase (HLE) with an IC(50) value of 0.86 μM.     

Redox Behaviour of Cymantrene Fischer Carbene Complexes in Designing Organometallic Multi‐tags

A series of Group 7 Fischer carbene complexes, [Cp(CO)₂Mn^I=C(OEt)Ar] (Cp=cyclopentadienyl, Ar=Th=thienyl ( 1 a ), Ar=Fu=furyl ( 2 a ), Ar=Fc=ferrocenyl ( 3 a )) and biscarbene complexes, [Cp(CO)₂Mn?C(OEt)?Ar′?(OEt)C?Mn(CO)₂Cp] (Ar′=Th′=2,5‐thienylene ( 1 b ), Ar′=Fu′=2,5‐furylene ( 2 b ), Ar′=Fc′=1,1′‐ferrocendiyl ( 3 b )) was synthesized and characterized. Chemical oxidation of [Cp(CO)₂Mn?C(OEt)Fc] ( 3 a ) and isolation of the oxidised species [3 a][PF₆] possessing a Mn^II centre proved possible below ?30 °C in dichloromethane solution. The ESR spectrum of the transiently stable radical cation, [3 a][PF₆] , confirmed the presence of a low‐spin Mn^II centre characterized by a rhombic g tensor (g_x=1.975, g_y=2.007 and g_z=2.130) in frozen dichloromethane at 77 K with ⁵⁵ Mn hyperfine coupling constants A₁, A₂ and A₃ of 115, 33 and 43 G, respectively. Electrochemical studies demonstrated the influence of the Ar substituent on the oxidation potential. All complexes showed that the redox potentials of carbene double bond reduction and Mn^I oxidation were dependent on the type of Ar group, but only 3 b showed resolved oxidations for the two Mn^I centres. Surprisingly, Mn^I oxidation occurs at lower potentials than ferrocenyl oxidation. Density functional theory (DFT) calculations were carried out to delineate the nature of the species involved in the oxidation and reduction processes and clearly confirm that oxidation of Mn^I is favoured over that of ferrocene.     

Competitive Molecular‐/Ion‐Recognition Responsive Characteristics of Poly(N‐isopropylacrylamide‐co‐benzo‐12‐crown‐4‐acrylamide) Copolymers with Benzo‐12‐crown‐4 as Both Guest and Host Units

Novel dual molecular‐ and ion‐recognition responsive poly(N‐isopropylacrylamide‐co‐benzo‐12‐crown‐4‐acrylamide) (PNB₁₂C₄) linear copolymers with benzo‐12‐crown‐4 (B12C4) as both guest and host units are prepared. The copolymers exhibit highly selective sensitivities toward γ‐cyclodextrin (γ‐CD) and Na⁺. The presence of γ‐CD induces the lower critical solution temperature (LCST) of PNB₁₂C₄ copolymer to shift to a higher value due to the formation of 1:1 γ‐CD/B12C4 host‐guest inclusion complexes, while Na⁺ causes a negative shift in LCST due to the formation of 2:1 “sandwich” B12C4/Na⁺ host‐guest complexes. Regardless of the complexation order, when γ‐CD and Na⁺ coexist with PNB₁₂C₄, competitive complexation actions of B12C4 as both guest and host units toward γ‐CD and Na⁺ finally form equilibrium 2:2:1 γ‐CD/B12C4/Na⁺ composite complexes, and the final LCST values of PNB₁₂C₄ copolymer reach almost the same level. The results provide valuable guidance for designing and applying PNB₁₂C₄‐based smart materials in various applications.

     

Methyl 2‐acetamido‐2‐deoxy‐β‐d‐glucopyranoside dihydrate and methyl 2‐formamido‐2‐deoxy‐β‐d‐glucopyranoside

Methyl 2‐acetamido‐2‐deoxy‐β‐d ‐glucopyranoside (β‐GlcNAcOCH₃), (I), crystallizes from water as a dihydrate, C₉H₁₇NO₆·H₂O, containing two independent molecules [denoted (IA) and (IB)] in the asymmetric unit, whereas the crystal structure of methyl 2‐formamido‐2‐deoxy‐β‐d ‐glucopyranoside (β‐GlcNFmOCH₃), (II), C₈H₁₅NO₆, also obtained from water, is devoid of solvent water molecules. The two molecules of (I) assume distorted ⁴C₁ chair conformations. Values of ϕ for (IA) and (IB) indicate ring distortions towards B_C2,C5 and ^C3,O5B, respectively. By comparison, (II) shows considerably more ring distortion than molecules (IA) and (IB), despite the less bulky N‐acyl side chain. Distortion towards B_C2,C5 was observed for (II), similar to the findings for (IA). The amide bond conformation in each of (IA), (IB) and (II) is trans, and the conformation about the C—N bond is anti (C—H is approximately anti to N—H), although the conformation about the latter bond within this group varies by ∼16°. The conformation of the exocyclic hydroxymethyl group was found to be gt in each of (IA), (IB) and (II). Comparison of the X‐ray structures of (I) and (II) with those of other GlcNAc mono‐ and disaccharides shows that GlcNAc aldohexopyranosyl rings can be distorted over a wide range of geometries in the solid state.     

Hydrogels Composed of Organic Amphiphiles and α‐Cyclodextrin: Supramolecular Networks of Their Pseudorotaxanes in Aqueous Media

Mixtures of N‐alkyl pyridinium compounds [py‐N‐(CH₂)_nOC₆H₃‐3,5‐(OMe)₂]⁺(X^?) ( 1b Cl: n=10, X=Cl; 1c Br: n=12, X=Br) and α‐cyclodextrin (α‐CD) form supramolecular hydrogels in aqueous media. The concentrations of the two components influences the sol–gel transition temperature, which ranges from 7 to 67 °C. Washing the hydrogel with acetone or evaporation of water left the xerogel, and ¹³C CP/MAS NMR measurements, powder X‐ray diffraction (XRD), and scanning electron microscopy (SEM) revealed that the xerogel of 1b Cl (or 1c Br) and α‐CD was composed of pseudorotaxanes with high crystallinity. ¹³C{¹H} and ¹H NMR spectra of the gel revealed the detailed composition of the components. The gel from 1b Cl and α‐CD contains the corresponding [2]‐ and [3]pseudorotaxanes, [ 1b? (α‐CD)]Br and [ 1b? (α‐CD)₂]Br, while that from 1c Br and α‐CD consists mainly of [3]pseudorotaxane [ 1c? (α‐CD)₂]Br. 2D ROESY ¹H NMR measurements suggested intermolecular contact of 3,5‐dimethoxyphenyl and pyridyl end groups of the axle component. The presence of the [3]pseudorotaxane is indispensable for gel formation. Thus, intermolecular interaction between the end groups of the axle component and that between α‐CDs of the [3]pseudorotaxane contribute to formation of the network. The supramolecular gels were transformed into sols by adding denaturing agents such as urea, C₆H₃‐1,3,5‐(OH)₃, and [py‐N‐nBu]⁺(Cl^?).     

Arylethyl (= Phenylethanoid) Glycosides and Oligosaccharide from the Stem of Cistanche tubulosa

Three new analogues of the arylethyl (= phenylethanoid) glycoside echinacoside ( 5 ), namely cistantubulosides A ( 1 ), B₁/B₂ ( 2a / 2b ), and C₁/C₂ ( 3a / 3b ), and one new oligosaccharide, cistantubulose A₁/A₂ ( 4a / 4b ), were isolated from the stems of Cistanche tubulosa (Schenk ) R. Wight , together with five known compounds, i.e., campneoside I, campneoside II ( 6 ), echinacoside ( 5 ), tubuloside, and cistanoside F. Among the compounds isolated, 2a / 2b, 3a / 3b, 4a / 4b , campneoside I, campneoside II ( 6 ), and cistanoside F each consisted of a pair of epimers. The structures of the new compounds were elucidated on the basis of spectral data.     

1-(2′-Deoxy-β-D-xylofuranosyl)thymine Building Blocks for Solid-Phase Synthesis and Properties of Oligo(2′-Deoxyxylonucleotides)

1-(2′-Deoxy-β-D -threo-pentofuranosyl)thymine (= 1-(2′-deoxy-β-D -xylofuranosyl)thymine; xT_d; 2 ) was converted into its phosphonate 3b as well as its 2-cyanoethyl phosphoramidite 3c . Both compounds were used for solid-phase synthesis of d[(xT)₁₂-T] ( 5 ), representing the first DNA fragment build up from 3′–5′-linked 2′-deoxy--β-D -xylonucleosides. Moreover, xT_d was introduced into the innermost part of the self-complementary dodecamer d(G-T-A-G-A-A-xT-xT-C-T-A-C)₂ (9). The CD spectrum of d[(xT)₁₂–T] ( 5 ) exhibits reversed Cotton effects compared to d(T₁₂) ( 6 ; see Fig. 1), implying a left-handed single strand. With d(A₁₂) ( 7 ) it could be hybridized to form a propably Left-handed double strand d(A₁₂) · d[(xT)₁₂–T] ( 7 · 5 ) which was confirmed by melting experiments in combination with temperature-dependent CD spectroscopy. While 5 was hydrolyzed by snake-venom phosphodiesterase, it was resistant towards calf-spleen phosphodiesterase. The modified, self-complementary duplex 9 was hydrolyzed completely by snake-venom phosphodiesterase, at a twelvefold slower rate compared to unmodified 8 ; calf-spleen phosphodiesterase hydrolyzed 9 only partially.     

A Novel BODIPY‐Based Low‐Band‐Gap Small‐Molecule Acceptor for Efficient Non‐fullerene Polymer Solar Cells

We report herein an efficient A¹‐C≡C‐A²‐C≡C‐A¹ type small‐molecule 4,4'‐difluoro‐4‐bora‐3a,4a‐diaza‐s‐ indacene (BODIPY) acceptor (A¹=BODIPY and A²=diketopyrrolopyrrole (DPP)) by following the A‐to‐A excited electron delocalization via the BODIPY meso ‐position, the inherent directionality for the excited electron delocalization. The lowest unoccupied molecular orbital (LUMO) delocalizes across over whole the two flanking A¹ and the central A², and the highest occupied molecular orbital (HOMO) localizes dominantly on the ‐C≡C‐DPP‐C≡C‐ segment. The excited electron upon light excitation of the DPP segment delocalizes over both the BODIPY and DPP segments. The acceptor in chloroform shows an unprecedented plateau‐like broad absorption between 550 and 700 nm with a large FWHM value of 195 nm. Upon transition into solid film, the acceptor shows absorption in the whole near ultraviolet‐visible‐near infrared wavelength region (300‐830 nm) with a low band gap of 1.5 eV and a maximum absorptivity of 0.85×10⁵ cm^‐1. Introduction of the ethynyl spacer between the A¹ and A² and the close BODIPY‐to‐DPP LUMO energy levels are crucial for the excited π−electron delocalization across over whole the conjugation backbone. A power conversion efficiency of 6.60% was obtained from the ternary non‐fullerene solar cell with PTB7‐Th:p ‐DTS(FBTTh₂)₂ (0.5 : 0.5) as the donor materials, which is the highest value among the non‐fullerene organic solar cells with BODIPY as the electron acceptor material.     

Difluorenyl carbo‐Benzenes: Synthesis,Electronic Structure,and Two‐Photon Absorption Properties of Hydrocarbon Quadrupolar Chromophores

The synthesis, crystal and electronic structures, and one‐ and two‐photon absorption properties of two quadrupolar fluorenyl‐substituted tetraphenyl carbo‐benzenes are described. These all‐hydrocarbon chromophores, differing in the nature of the linkers between the fluorenyl substituents and the carbo‐benzene core (C?C bonds for 3 a , C?C?C?C expanders for 3 b ), exhibit quasi–superimposable one‐photon absorption (1PA) spectra but different two‐photon absorption (2PA) cross‐sections σ_2PA. Z‐scan measurements (under NIR femtosecond excitation) indeed showed that the C?C expansion results in an approximately twofold increase in the σ_2PA value, from 336 to 656 GM (1 GM=10^?50 cm⁴ s molecule^?1 photon^?1) at λ=800 nm. The first excited states of A_u and A_g symmetry accounting for 1PA and 2PA, respectively, were calculated at the TDDFT level of theory and used for sum‐over‐state estimations of σ_2PA(λ_i), in which λ_i=2 hc/E_i, h is Planck’s constant, c is the speed of light, and E_i is the energy of the 2PA‐allowed transition. The calculated σ_2PA values of 227 GM at 687 nm for 3 a and 349 GM at 708 nm for 3 b are in agreement with the Z‐scan results.     

The analytical resolution of parallel first‐ and second‐order reaction mechanisms

Given the species A₁ and A₂, the competition among the three different elementary processes (1) (2) (3) is frequently found in thermal and photochemical reaction systems. In the present paper, an analytical resolution of the system (1)–(3), performed under plausible contour conditions, namely, finite initial molar concentrations for both reactants, [A₂]₀ and [A₁]₀, and nonzero reaction rate coefficients k₁, k₂, and k₃, leads to the equation [A₁] = ((δ[A₂]^γ ? [A₂])/β) ? α, where α = k₁/2k₃, γ = β + 1 = 2k₃/k₂, and δ = ([A₂]₀ + β[A₁]₀ + β α))/[A₂]₀^γ. The comparison with a numerical integration employing the fourth‐order Runge–Kutta algorithm for the well‐known case of the oxidation of organic compounds by ferrate ion is performed. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 562–566, 2010     

Chemical bond breaking/forming as a Franck–Condon electronic process

We describe chemical bond changes as Franck–Condon electronic processes within a new theoretical ansatz that we call ‘rigged’ Born–Oppenheimer (R-BO) approach. The notion of the separability of nuclear and electron states implied in the standard Born–Oppenheimer (BO) scheme is retained. However, in the present scheme the electronic wave functions do not depend upon the nuclear coordinate (R-space). The new functions are obtained from an auxiliary Hamiltonian corresponding to the electronic system (r-coordinates) submitted to a Coulomb potential generated by external sources of charges in real space (α-coordinates) instead of massive nuclear objects. A stationary arrangement characterized by the coordinates α_0A, is determined by a particular electronic wave function, ψ(r;α_0A); it is only at this stationary point, where an electronic Schrödinger equation: H_e(r,α_0A)|Ψ(r;α_0A)=E(α_0A)|Ψ(r;α_0A) must hold. This equation permits us to use modern electronic methods based upon analytic first and second derivatives to construct model electronic wave functions and stationary geometry for external sources. If the set of wave functions {Ψ(r;α_0A)} is made orthogonal, the energy functional in α-space, E(α;α_0A)=Ψ(r;α_0A)|H_e(r,α_0A)|Ψ(r;α_0A) is isomorphic to a potential energy function in R-space: E(R;α_0A)=Ψ(r;α_0A)|H_e(r,R)|Ψ(r;α_0A). This functional defines, by hypothesis, a trapping convex potential in R-space and the nuclear quantum states are determined by a particular Schrödinger equation. The total wave function for the chemical species A reads as a product of our electronic wave function with the nuclear wave function (Ξ_ik(R;α_0A)): Φ_ik(r,R)=Ψ_i(r,α_0A)Ξ_ik(R;α_0A). This approach facilitates the introduction of molecular frame without restrictions in the R-space. Two molecules (characterized with different electronic spectra) that are decomposable into the same number of particles (isomers) have the same Coulomb Hamiltonian and they are then characterized by different electronic wave functions for which no R-coordinate ‘deformation’ can possibly change its electronic structure. A bond breaking/forming process must be formally described as a spectroscopic-like electronic process. The theory provides an alternative to the adiabatic as well as the diabatic scheme for understanding molecular processes. As an illustration of the present ideas, the reaction of H₂+CO leading to formaldehyde is examined in some detail.     

Hydro­gen bonding and C—H⃛O interactions in 2‐[1‐(1‐naphthyl)ethyl]benzoic acid at 150 K

The title acid, C₁₉H₁₆O₂, crystallized in the centrosymmetric space group Pnna with three mol­ecules in the asymmetric unit (apparently the first reported instance of Z′ = 3 in this space group). Four intermolecular hydrogen bonds have O_D?O_A distances of 2.660 (2), 2.594 (2), 2.633 (2) and 2.646 (2) Å, and angles of 177 (2), 179 (2), 175 (2) and 175 (2)°. The four hydrogen bonds form two R(8) cyclic dimers, one about a twofold axis. Five leading intermolecular C—H?O interactions are present. Although first‐ and second‐level graph sets involving these nine interactions are dominated by finite patterns, a three‐dimensional network becomes evident upon analysis of higher‐level graphs. A number of intramolecular C—H?O interactions are also present.     

Veronicafolin－β-环糊精的物化表征及Veronicafolin－羟丙基-β-环糊精包合物溶解性的增强

用氢谱、红外光谱、X-射线粉末衍射、热分析、元素分析等测试方法研究了Veronicafolin (3,5,4′-三羟基-6,7,3′-三甲氧基黄酮) 和β-环糊精 (β-CD) 的固体包合物的谱学特征。元素分析结果显示形成Veronicafolin-β-CD·20H2O包合物，其中C：39.58%, H: 5.75%，表明包合物中主客体比为1∶1。该包合类型属于A_L-型。通过紫外-可见分光光度法研究了在羟丙基-β-环糊精（HP-β-CD）的存在下Veronicafolin的相溶解度曲线，测得校正曲线为y = 24148x + 0.0075 (r=0.9999)，相溶解曲线为y=0.4738x-2.0×10^-7 (r=0.9490)，包结平衡常数Ks为4.5×10⁶mol-1。HP-β-CD提高了黄酮醇Veronicafolin的溶解度。     

Methyl 4‐O‐β‐D‐mannopyranosyl β‐D‐xylopyranoside

Methyl β‐D‐mannopyranosyl‐(1→4)‐β‐D‐xylopyranoside, C₁₂H₂₂O₁₀, (I), crystallizes as colorless needles from water, with two crystallographically independent molecules, (IA) and (IB), comprising the asymmetric unit. The internal glycosidic linkage conformation in molecule (IA) is characterized by a ϕ′ torsion angle (O5′_Man—C1′_Man—O1′_Man—C4_Xyl; Man is mannose and Xyl is xylose) of −88.38 (17)° and a ψ′ torsion angle (C1′_Man—O1′_Man—C4_Xyl—C5_Xyl) of −149.22 (15)°, whereas the corresponding torsion angles in molecule (IB) are −89.82 (17) and −159.98 (14)°, respectively. Ring atom numbering conforms to the convention in which C1 denotes the anomeric C atom, and C5 and C6 denote the hydroxymethyl (–CH₂OH) C atom in the β‐Xylp and β‐Manp residues, respectively. By comparison, the internal glycosidic linkage in the major disorder component of the structurally related disaccharide, methyl β‐D‐galactopyranosyl‐(1→4)‐β‐D‐xylopyranoside), (II) [Zhang, Oliver & Serriani (2012). Acta Cryst. C 68 , o7–o11], is characterized by ϕ′ = −85.7 (6)° and ψ′ = −141.6 (8)°. Inter‐residue hydrogen bonding is observed between atoms O3_Xyl and O5′_Man in both (IA) and (IB) [O3_Xyl...O5′_Man internuclear distances = 2.7268 (16) and 2.6920 (17) Å, respectively], analogous to the inter‐residue hydrogen bond detected between atoms O3_Xyl and O5′_Gal in (II). Exocyclic hydroxymethyl group conformation in the β‐Manp residue of (IA) is gauche–gauche, whereas that in the β‐Manp residue of (IB) is gauche–trans.     

Highly Antiplasmodial Non‐Natural Oxidative Products of Dioncophylline A: Synthesis,Absolute Configuration,and Conformational Stability

Four new compounds, the monomeric dioncotetralones A ( 6 a ) and B ( 6 b ) and the dimeric compounds jozimine A₃ ( 7 ) and jozimine A₄ ( 9 ), were semi‐synthesized from the natural product dioncophylline A ( 4 ) and its 5′‐O‐demethylated derivative ( 5 ), respectively, under phenol oxidative reaction conditions. Dioncotetralones A ( 6 a ) and B ( 6 b ) possess an unprecedented Z‐configured double bond, in contrast to the classic biaryl axis that is present in the precursor dioncophylline A ( 4 ), and an additional stereogenic center at the C2′ atom was generated due to the dearomatization. The resulting steric repulsion forced the expected planar double bond into a helical distorted conformation. The homocoupling of 5 yielded compounds 7 and 9 , the latter of which is the first sp³–sp² coupled product of a monomeric naphthylisoquinoline with a reduced one and, thus, contains a newly generated stereogenic center. The full stereostructures of 6 a , 6 b , 7 , and 9 were successfully elucidated by the interplay of spectroscopic methods (1D/2D NMR and electronic circular‐dichroism spectroscopy) in combination with quantum‐chemical calculations. In addition, compounds 6 a and 7 exhibited high antiplasmodial activities with excellent half‐maximal inhibitory concentration values.     

A hybrid‐type,chiral π‐conjugated polymer wrapped with polyhedral oligomeric silsesquioxanes

A novel hybrid‐type chiral binaphthyl‐based polyarylene derivative with polyhedral oligomeric silsesquioxanes (POSS) units 2a was prepared by Suzuki–Miyaura coupling polymerization from a chiral (R)‐6,6′‐dibromo‐2,2′‐diPOSS‐substituted 1,1′‐binaphthyl derivative 1a and p‐biphenylene diboronic acid. As a reference, a binaphthyl‐based polyarylene derivative without POSS unit 2b was also prepared. The obtained polymers were studied with thermogravimetric analysis, optical rotations, circular dichroism (CD), ultraviolet‐visible, and photoluminescence (PL) spectra. Gel permeation chromatography measurements of 2a and 2b showed that their number‐average molecular weights were 13,300 and 16,500, respectively. The thermal stability of POSS‐modified polymer 2a (temperature of 10% weight loss; T₁₀ = 380 °C) was extremely high compared with that of polymer without POSS unit 2b (T₁₀ = 335 °C) due to the siliceous bulky POSS segments on the side chains. The specific optical rotation [α]_D was ?66.7° (c 0.06, CHCl₃) for 2a and ?62.3° (c 0.06, CHCl₃) for 2b . The CD spectra showed that these two polymers had very similar and strong Cotton effects. Film polymer 2a showed almost the same PL spectrum as that in dilute CHCl₃ solution, indicating that bulky POSS units strongly suppressed intermolecular aggregation of the π‐conjugated polymer backbone. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6035–6040, 2008     

Synthesis of hyperbranched polyacetals via an + b2‐type polyaddition (n = 3, 8, 18, and 21): Candidate resists for extreme ultraviolet lithography

Polyaddition (A_n + B₂) reactions of 1,1,1‐tris(4‐hydoxyphenyl) ethane (THPE; A₃‐type monomer), calix[4]resorcinarene (CRA[4]; A₈‐type monomer), α‐cyclodextrin (α‐CD; A₁₈‐type monomer), and β‐cyclodextrin (β‐CD; A₂₁‐type monomer) with 1,4‐bis(4‐vinyloxy)cyclohexane (BVOC; B₂‐type monomer) afforded corresponding soluble hyperbranched polyacetals. The physical properties, including solubility, thermal stability, and film‐forming ability, the ultraviolet‐induced degradation reactivity, and the solubility‐switch in an extreme ultraviolet (EUV) exposure tool indicated that poly(THPE‐co‐BVOC) and poly(CRA[4]‐co‐BVOC) are candidate next‐generation photo‐resists. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2343–2350     

Synthesis and self‐assembly of well‐defined cyclodextrin‐centered amphiphilic A14B7 multimiktoarm star copolymers based on poly(ε‐caprolactone) and poly(acrylic acid)

Novel amphiphilic A₁₄B₇ multimiktoarm star copolymers composed of 14 poly(ε‐caprolactone) (PCL) arms and 7 poly(acrylic acid) (PAA) arms with β‐cyclodextrin (β‐CD) as core moiety were synthesized by the combination of controlled ring‐opening polymerization (CROP) and atom transfer radical polymerization (ATRP). 14‐Arm star PCL homopolymers (CDSi‐SPCL) were first synthesized by the CROP of CL using per‐6‐(tert‐butyldimethylsilyl)‐β‐CD as the multifunctional initiator in the presence of Sn(Oct)₂ at 125 °C. Subsequently, the hydroxyl end groups of CDSi‐SPCL were blocked by acetyl chloride. After desilylation of the tert‐butyldimethylsilyl ether groups from the β‐CD core, 7 ATRP initiating sites were introduced by treating with 2‐bromoisobutyryl bromide, which further initiated ATRP of tert‐butyl acrylate (tBA) to prepare well‐defined A₁₄B₇ multimiktoarm star copolymers [CDS(PCL‐PtBA)]. Their molecular structures and physical properties were in detail characterized by ¹H NMR, SEC‐MALLS, and DSC. The selective hydrolysis of tert‐butyl ester groups of the PtBA block gave the amphiphilic A₁₄B₇ multimiktoarm star copolymers [CDS(PCL‐PAA)]. These amphiphilic copolymers could self‐assemble into multimorphological aggregates in aqueous solution, which were characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM) and atomic force microscopy (AFM). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2961–2974, 2010     

Neue Zinn‐reiche Stannide der Systeme AII‐Al‐Sn (AII = Ca,Sr, Ba)

New Tin‐rich Stannides of the Systems A^II‐Al‐Sn (A^II = Ca, Sr, Ba) Four new tin‐rich intermetallics of the ternary systems Ca/Sr/Ba‐Al‐Sn were synthesized from stoichiometric amounts of the elements at maximum temperatures of 1200 °C. Their crystal structures, representing two new types, have been determined using single crystal x‐ray diffraction. Close to the 1:1 composition, the structures of the two isotypic compounds A₁₈[Al₄(Al/Sn)₂Sn₄][Sn₄][Sn]₂ (overall composition A₉M₈; A = Sr/Ba, tetragonal, space group P4/mbm, a = 1325.9(1)/1378.6(1), c = 1272.8(2)/1305.4(1) pm, Z = 4, R1 = 0.0430/0.0293) contain three different anionic Sn/Al building units: Isolated Sn atoms (motif I) coordinated by the alkaline earth cations only (comparable to Ca₂Sn), linear Sn chains (II), which are comparable to the anions in trielides related to the W₅Si₃ structure type and finally octahedral clusters [Al₄M₂Sn₄] (III), composed of four Al atoms forming the center plane, two statistically occupied Al/Sn atoms at the apexes and four exohedral Sn attached to Al. Close to the AM₂ composition, two isotypic tin‐rich intermetallics A₉[Al₃Sn₂][(Sn/Al)₄]Sn₆ (overall composition A₉M₁₅; A = Ca/Sr; space group C2/m, a = 2175.2(1)/2231.0(2), b = 1210.8(1)/1247.0(1), c = 1007.4(1)/1042.0(2) pm, β = 103.38(1)/103.42(1)°, Z = 2, R1 = 0.0541/0.0378) are formed. Their structure is best described as a complex three‐dimensional network, that can be considered to consist of the building units of the binary border phases too, i.e. linear zig‐zag chains of Sn (motif I) like in CaSn, ladders of four‐bonded Sn/Al atoms (II) like in SrAl₂ and trigonal‐bipyramidal clusters [Al₃Sn₂] (III) also present in Ba₃Al₅. Despite the complex structures, some statistically occupied Al/Sn positions and the small disorder of one building unit, the bonding in both structure types can be interpreted using the Zintl concept and Wade's electron counting rules when taking partial Sn‐Sn bonds into account.     

Synthesis,Characterization, and Crystal Structure of the New Schiff‐Bases derived from 1,2,4‐Triazole and the Structure of [(PPh3)2Cu(AMTT)]NO3·EtOH (AMTT = 4‐Amino‐5‐methyl‐2H‐1,2,4‐triazole‐3(4H)‐thione)

The reactions of 4‐amino‐5‐methyl‐2H‐1,2,4‐triazole‐3(4H)‐thione (AMTT, L1 ) with 2‐thiophen carbaldehyde, salicylaldehyde and 2‐nitrobenzaldehyde in methanol led to the corresponding Schiff‐bases ( L1a‐c ). The reaction of L1 with [(PPh₃)₂Cu]NO₃ in ethanol gave the ionic complex [(PPh₃)₂Cu(L1)]NO₃·EtOH ( 2 ) All compounds were characterized by infrared spectroscopy, elemental analyses as well as by X‐ray diffraction studies. Crystal data for L1a at 20 °C: space group P2₁/n with a = 439.6(2), b = 2074.0(9), c = 1112.8(4) pm, β = 93.51(3)°, Z = 4, R₁ = 0.0406, L1b at ?80 °C: space group P2₁/n with a = 1268.9(2), b = 739.3(1), c = 1272.5(1) pm, β = 117.97(1)°, Z = 4, R₁ = 0.0361, L1c at ?80 °C: space group P2₁/n with a = 847.8(1), b = 1502.9(2), c = 981.5(2) pm, β = 110.34(1)°, Z = 4, R₁ = 0.0376 and for 2 at ?80 °C: space group with a = 1247.8(1), b = 1270.3(1), c = 1387.5(1) pm, α = 84.32(1)°, β = 84.71(1)°, γ = 63.12(1)°, Z = 2, R₁ = 0.0539.