Design,synthesis and structure determination of new inherently chiral para-bromoalkoxycalix[4]arenes

The preparative method for the synthesis of inherently chiral para-bromoalkoxycalix[4]arenes based on para-bromination, stepwise regioselective debenzoylation and the following alkylation of the readily available 25-propoxy-26,27-dibenzoyloxycalix[4]arene with propyl bromide or (R)-N-(1-phenylethyl)bromoacetamide has been developed. Three types of the inherently chiral calix[4]arenes in cone or partial cone conformations with asymmetrical (_AHHH^HBHH, _AAHH^HBHH, _AHBH^HCHH) substitution of both upper and lower rims have been obtained in racemic, diastereomerically pure or enantiomerically pure forms. Their structure and the absolute configuration have been determined by NMR and X-ray.     

Effective nonenzymatic kinetic resolution of racemic m-nitro-substituted inherently chiral aminocalix[4]arenes

Effective nonenzymatic kinetic resolution of racemic m-nitro-substituted inherently chiral aminocalix[4]arenes with Boc-l-proline as the acylating reagent is described, which provides an efficient and convenient method for the enantioselective synthesis of meta-substituted aminocalix[4]arenes.     

Facile synthesis and optical resolution of inherently chiral fluorescent calix[4]crowns: enantioselective recognition towards chiral leucinol

A series of tri-O-alkylated inherently chiral fluorescent calix[4]crowns in the cone conformations and a series of tetra-O-alkylated inherently chiral fluorescent calix[4]crowns in the partial cone conformations have been synthesized. By condensing with chiral auxiliary (S)-BINOL, the resulting diastereomers could be separated via preparative TLC. We found that the size of the crown moiety effected the separation of the diastereomers. Further, removal of the BINOL unit by hydrolysis furnished pairs of enantiomers with optical purity. Moreover, we found that a tetra-O-alkylated inherently chiral fluorescent calix[4]crown-6 in the partial cone conformation 6c showed considerable enantioselective recognition capability towards chiral leucinol.     

Solid-state 13C NMR investigations of cyclophanes: [2.2]paracyclophane and 1,8-dioxa[8](2,7)pyrenophane

Solid-state NMR (ssNMR) and ab initio quantum mechanical calculations are used in order to understand and to better characterize the molecular conformation and properties of [2.2]paracyclophane and 1,8-dioxa[8](2,7)pyrenophane. Both molecules are cyclophanes, consisting of an aromatic ring assembly and a cyclic aliphatic chain connected to both ends of the aromatic portion. The aliphatic chain causes curvature in the six-membered aromatic ring structures. This led us to examine how the ring strain due to curvature affects the chemical shifts. Using X-ray structures of both [2.2]paracyclophane and 1,8-dioxa[8](2,7)pyrenophane as our starting model, we calculate the chemical shielding tensors and compare these data with those collected from the (13)C ssNMR FIREMAT experiment. We define curvature of [2.2]paracyclophane and 1,8-dioxa[8](2,7)pyrenophane using the π-orbital axis vector (POAV) pyramidalization angle (θ(p)).     

Synthesis, optical resolution and absolute configuration of inherently chiral calixarene carboxylic acids

Both enantiomers of inherently chiral calixarene carboxylic acids with ABCD substitution patterns have been prepared by the benzoylation of 25-propoxy-27-(R)-N-(α-phenylethyl)amidomethyloxycalix[4]arene followed by resolution of the diastereomers formed, monobromination of them and removal of the benzoyl and α-phenylethylamide auxiliary groups. The absolute configuration of the calixarenes obtained has been established by X-ray analysis. Preliminary study of the chiral recognition properties of calixarene carboxylic acid was performed.     

Synthesis and characterization of an inherently chiral calix[6]arene in the 1,4-alternate conformation

An inherently chiral calix[6]arene possessing a C₂-symmetric A-B-H substitution pattern was synthesized via a two step process starting from the parent hexa-t-butylcalix[6]arene. The racemic, inherently chiral compound exists as a single isomer with the 1,4-alternate conformation. The inherent chirality was confirmed by treatment of the racemic compound with Pirkle’s reagent to form diastereomeric complexes in solution.     

Ruthenium(II) complexes with tetradentate pyridylthioazoimine [N,S,N,N] ligands: Synthesis, crystal structure and spectroscopy

The Ru(II) complexes cis-[Ru(L)Cl₂] (C1-C3) of novel tetradentate NSNN ligands (L) {where L is C₅H₄N-CH₂-S-C₆H₄NC(COCH₃)-NN-C₆H₄X, and X is H (L1), CH₃ (L2) and Br (L3)}, were synthesized and characterized by spectroscopy (IR, UV/vis and NMR), cyclic voltammetry and crystallography. The tetradentate ligands were isolated as the amidrazones H₂L {where H₂L is C₅H₄N-CH₂-S-C₆H₄NH-C(COCH₃)N-NH-C₆H₄X and X is H (H₂L1), CH₃ (H₂L2) and Br (H₂L3)} as shown by crystallography of H₂L1, but oxidize to azoimines during the formation of the Ru(II) complexes. A crystallographic analysis of C1 showed that the Ru(II) centre is in a distorted octahedral coordination sphere in which the tetradentate ligand occupies three equatorial sites and one axial site (two azoimine nitrogens and a thio sulfur in the equatorial plane and an axial pyridine nitrogen) and two chlorides occupying axial and equatorial coordination sites. The Ru(II) oxidation state is greatly stabilized by the novel tetradentate ligand, showing Ru(III/II) couples ranging from 1.43 to 1.51 V. The absorption spectrum of C1 in acetonitrile was modelled by time-dependent density functional theory.     

Synthesis and optical resolution of a series of inherently chiral calix[4]crowns with cone and partial cone conformations

A series of inherently chiral calix[4]arenes with cone and partial cone conformations and with crown ether moieties of variable size have been readily synthesized. By taking advantage of the carboxy appendage on the lower rim, these were condensed with the chiral auxiliary (S)-BINOL to form diastereomers which, in most cases, could be separated by preparative TLC, or more desirably, by column chromatography on silica gel (diastereomeric excess >99 % based on HPLC analysis). Seven enantiopure antipodes of inherently chiral calix[4]crowns were obtained after hydrolysis. It has been found that both the size of the crown moiety and alkylation of the last phenolic hydroxy group (accompanied with or without a change in the conformation) affect the separation of the diastereomers.     

Synthesis,crystal structure,and thermal behavior of Pt-based heterometallics [PtPy4](FcCOO)2 and trans-[PtPy2(FcCOO)2]

Novel square-planar Pt-based heterometallic complexes with ferrocenecarboxylic acid were prepared in two steps from (tetrapyridine)platinum diacetate [PtPy₄](OAc)₂. The crystal structure of [PtPy₄](FcCOO)₂ and [PtPy₂(FcCOO)₂] was established by single crystal X-ray diffraction. Subsequent thermal transformation of a trinuclear compound [PtPy₂(FcCOO)₂] to a bimetallic Pt–Fe phase was studied by XAFS techniques.     

Helically chiral functionalized [6]helicene: Synthesis,optical resolution,and photophysical properties

A short and efficient synthetic pathway leading to a new chiral π-conjugated system is reported. The X-ray structure of the target compound was determined and showed a helical conformation. Its resolution was successfully accomplished, leading to two enantiomers in high optical purity, and their chiroptical properties were examined experimentally. The photophysical properties of the organic material were also evaluated, showing an emission in the visible region, and HOMO and LUMO levels have been estimated experimentally, demonstrating an electrochemical band gap of 2.37 eV.     

1,6-亚甲基桥[10]轮烯并[3,4-g]-蒽醌衍生物的合成

采用无溶剂合成法,以1,6-亚甲基桥[10]轮烯-3,4-二甲酸酐为原料,Zr OCl2·8H2O/Na Cl为催化剂,于165℃下分别与取代苯经Friedel-Crafts缩合反应合成了4个新型的1,6-亚甲基桥[10]轮烯并[3,4-g]-蒽醌衍生物,其结构经1H NMR,13C NMR,IR,MS和HR-MS表征。     

N,N,N,N-四乙酰氧甲基-1,5-二苯基-2,4,6,8-四氮杂双环[3.3.0]-3,7-辛二酮的合成及晶体结构研究

以苯基苷脲为原料设计合成N,N,N,N-四乙酰氧甲基-1,5-二苯基-2,4,6,8-四氮杂双环[3.3.0]-3,7-辛二酮,并对其结构进行了X-单晶衍射表征.结果表明:该化合物晶体属于单斜晶系,空间群,P_(21/n),a=1.102 3(7)nm,b=1.741 3(11)nm,c=1.261 2(8)nm,α=90°,β=99.601(17)°,γ=90°,V=2.386 88 nm~3,Z=4,R(1)=0.075 9.量子化学计算结果表明,化合物的偶极矩为1.530×10~(-29) C·m.     

Synthesis and structure of 1,11-O-benzeno[2]orthocyclo[2](4,5)troponophanes

The title compound, the first stacked [2.2]orthotroponophane, was synthesized to elucidate the transannular interaction between upper and lower decks.     

Synthesis and crystal structure of an O-silylated hexahomotriazacalix[3]arene

The first synthesis of an O-silylated derivative of a hexahomotriazacalix[3]arene has been achieved using 1-(trimethylsilyl)imidazole (TMSIM), 1,1,1,3,3,3-hexamethyldisilazane (HMDS), or bis(trimethylsilyl)trifluoroacetamide (BSTFA) in acetronitrile. The cone isomer was formed selectively using TMSIM and HMDS; whereas a cone/partial cone mixture was obtained using BSTFA.     

Synthesis and crystal structure of tris[2-(N,N-dimethylthiocarbamoyl)benzimidazolato-1]cobalt(III)

Conditions for the formation of a CoL₃ complex, where L is the deprotonated benzimidazole-2-(N,N-dimethyl)carbothioamide molecule, are studied. The structure of the complex is determined by X-ray diffraction analysis. Each ligand in crystal of the complex is bonded to the metal atom by the bidentate chelate mode at the vertices of a distorted octahedron. The S and N atoms in the octahedron are in the cis-position to each other. All bonds with the same multiplicity in the ligands and in the CoS₃N₃ octahedron have almost the same length.     

Synthesis,complexation, and supramolecular assembly of 21,30-dithia-17,25-dimethyl-1,4,7,10,13- pentaoxa[13.3.3](1,2,6)cyclophane

[structure: see text] A crownophane consisting of a dithia[3.3]metacyclophane moiety was synthesized by employing a high dilution method. The crystal structure and complexation behavior of this crownophane was studied. A hydrogen-bonded linear supramolecular assembly using anion-Na(+)-crownophane-solvent as a synthon was observed in the solid state. This supramolecular assembly was also stabilized via an intermolecular S.H-C interaction.     

Synthesis,spectroscopic investigation,crystal and molecular structure of [ReCl2(N2COPh)(C10H14N2)(PPh3)2]

[ReCl₂(N₂COPh)(C₁₀H₁₄N₂)(PPh₃)₂] has been obtained in the reaction of benzoylhydrazido-Re(V) with an excess of nicotine. The [ReCl₂(N₂COPh)(C₁₀H₁₄N₂)(PPh₃)₂] complex crystallizes in the monoclinic space group P2₁/n. The complex was characterized by infrared, Ultaviolet-visible, ¹H NMR and magnetic measurements.     

Selective synthesis and crystal structure of [10]cycloparaphenylene

[10]Cycloparaphenylene ([10]CPP) was selectively synthesized in four steps in 13% overall yield from commercially available 4,4'-diiodobiphenyl by using mono-I-Sn exchange, Sn-Pt transmetalation, I-Pd exchange, and subsequent oxidative coupling reactions. The single-crystal X-ray structure of [10]CPP is described.