13,17,53,57-Tetraphenyl-13,17,53,57-tetrathio-3,7-dithia-1,5(1,5)-di(1,5-diaza-3,7-diphosphacyclooctana)-2,4,6,8(1,4)-tetrabenzenacyclooctaphane with an unusual conical-like conformation

1³,1⁷,5³,5⁷-tetraphenyl-1³,1⁷,5³,5⁷-tetrathio-3,7-dithia-1,5(1,5)-di(1,5-diaza-3,7-diphosphacyclooctana)-2,4,6,8(1,4)-tetrabenzenacyclooctaphane 2b was obtained by sulfurization of the corresponding macrocyclic tetraphosphine 1b. The structure of the inclusion complex of tetrasulfide 2b with DMF was investigated by the X-ray crystal structure analysis. A novel for this type of cyclophanes and relatively rare conical-like conformation of the macrocycle was found. A methyl group from one of the solvating DMF molecules penetrates the macrocyclic cavity of 2b from the side of the wider rim. According to quantum-chemical simulations, this may be the reason of the unusual conical conformation of 2b because the cavity of the macrocycles of this type is highly flexible. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Binding of 1,5-bis(p-sulfonatophenyl)-3,7-diphenyl-1,5-diaza-3,7-diphosphacyclooctane with tetra(methyl viologen) calix[4]resorcinol

Binding of an amphiphilic dianion 1,5-bis(p-sulfonatophenyl)-3,7-diphenyl-1,5-diaza-3,7-diphosphacyclooctane (APCO^2?) with an amphiphilic octacation tetra(methyl viologen) calix[4]resorcinol (MVCA⁸⁺) in media containing different amounts of water and DMSO using NaClO₄ or NaCl as supporting electrolytes was shown for the first time by cyclic voltammetry and spectrophotometry. The stoichiometry of the complex depends on the MVCA⁸⁺: APCO^2? ratio, medium, and supporting electrolyte. A 1: 1 charge-transfer complex is mainly formed (λ_max = 480 nm) in 30% DMSO at a ratio of the compounds of 1: 1. A similar 1: 1 complex of APCO^2? with a model compound methyl viologen MV²⁺ (λ_max = 482 nm) is formed under these conditions. A donor-acceptor interaction occurs between the acceptor viologen units and nitrogen-centered electron-donating fragments of the APCO^2? dianion. An increase in the content of APCO^2? in the solution leads to an additional binding of one (30 vol.% DMSO, water, NaClO₄) or two (30 vol.% DMSO, water, NaCl) particles of APCO^2? with the hydrophobic fragments of MVCA⁸⁺. The complexes aggregate to form insoluble precipitates in aqueous and water-DMSO media. A selective reversible electroswitching from the bound to free state of one of the three bound APCO^2? particles was performed when reducing MVCA⁸⁺ to MVCA^4·+ in a 30 vol.% DMSO/NaCl medium.     

Binding of 1,5-bis(p-sulfonatophenyl)-3,7-diphenyl-1,5-diaza-3,7-diphosphacyclooctane with tetramethylviologen calix[4]resorcin with a methyl radical in the resorcinol ring

The binding of the amphiphilic 1,5-bis(para-sulfonatophenyl)-3,7-diphenyl-1,5-diaza-3,7-diphosphacyclooctane dianion (APCO^2?) with the octacation of the amphiphilic tetramethylviologen calix[4]resorcin having a methyl radical in the resorcinol ring (MVCA-C ₁ ⁸⁺ ) in 30% aqueous DMSO in a 0.1M NaCl supporting solution was studied by various methods. The dianion was bound at the upper rim of calixresorcin due to the donor-acceptor interactions between the viologen acceptor units and the nitrogen- and phosphorus-centered electron-donor fragments of APCO^2? and at the lower rim due to hydrophobic interactions. The composition of the complex depended on the MVCA-C ₁ ⁸⁺ : APCO^2? ratio. The complexes aggregated, forming insoluble precipitates. MVCA-C ₁ ⁸⁺ -APCO^2? is a system with reversibly electro-switchable aggregation. The starting MVCA- ₁ ⁸⁺ octacation partially bound APCO^2?, a certain quantity of both substrates remaining in a free state in solution. The MVCA-C ₁ ^4+· tetraradical tetracation formed as a result of the reduction of MVCA-C ₁ ⁸⁺ completely bound APCO^2? due to hydrophobic interactions when the MVCA-C ₁ ⁸⁺ : APCO^2? ratio was 1: 3. The reversible oxidation of MVCA-C ₁ ^4+· to the starting MVCA-C ₁ ⁸⁺ octacation brought the system back to its starting state     

The gas-phase conformation of 3,7-dimethyl-3,7-diazabicyclo[3.3.1]nonane

The gas-phase conformation of the title compound (1) is discussed in reference to its photoelectron spectrum. The experimental lone-pair/lone-pair splitting (0.51 eV), when compared with that of similar diamines and with the results of three sets of MO calculations (MINDO/3, MNDO and STO-3G), leads to the conclusion that 1 exists in the chair-chair conformation. A remarkable sensitivity of the calculations to slight changes in the geometry is noted, and it is suggested that calculations of this type must include geometry-optimization. The question of through-space vs through-bond inteaction of the nitrogen lone pairs was explored by performing MNDO calculations in which the N-N resonance integrals were set to zero. These calculations indicate that in the chair-chair conformation the N-N interaction is mainly through-space. The ¹³CNMR and Ni(acac)₂-induced ¹³C shifts of 1 are discussed.     

The conformation and vibrational spectra of 1,5-hexadiene-3-yne (divinylacetylene) and perchloro-1,5-hexadiene-3-yne (perchlorodivinylacetylene)

Infrared spectra of 1,5-hexadiene-S-yne (divinylacetylene) have been recorded in the vapour phase, in solution and in the amorphous and crystalline solid states at 90 K in the region 4000–4020 cm^?1. Correspondingly, IR spectra ofperchloro-1,5-hexadiene-3-yne (perchlorodivinylacetylene) as a melt, as a solute in various solvents and as a solid at 90 K have been obtained. Raman spectra of the two compounds were recorded in the liquid (molten) state including polarization measurements, and as crystalline solids at 90 K.The spectral data indicate that each compound exists as one conformer only in the various states of aggregation. In divinylacetylene the molecular symmetry appears to be anti (C_2h) while for perchlorodivinylacetylene the symmetry is either C_2v (syn) or C₂ (gauche). Vibrational assignments for the spectra of both molecules are presented and the values are compared with the results of normal coordinate analyses.     

The absolute configuration and circular dichroism of (+)-(1,5)-diamino-triptycene

The absolute configuration of(+)-(1,5)-diamino-triptycene has been determined by calculation of the CD spectrum of the molecule and comparison with the experimental results of Tanaka et al.⁴ To achieve this the exciton theory of Weigang and Nugent³ has been extended to include terms representing the retardation of the electro-magnetic wave in the chromophores. The final results of the present study are in contradiction with those of Tanaka et al.^4a,b,c     

The crystal structure of 1,5-bis(3,5-dimethyl-2-hydroxybenzyl)-1,5-diazocan-2,6-dione

The study of the molecular geometry of 1,5-bis(3,5-dimethyl-2-hydroxybenzyl)-1,5-diazocan-2,6-dione (2) as determined by X-ray analysis is reported and compared with that of cyclodi-β-alanyl (3). Interestingly there are 1.5 molecules of 2 in the asymmetric unit, showing the two conformations (1 twist-boat- and 0.5 chair-type) with two parallel aromatic rings (from alternate twist-boat conformers) sandwiching the eight-membered ring of the centrosymmetric chair-type conformation. The twist-boat is shown by pmr spectroscopy to be the only significantly populated conformer at low temperature in deuteriodichloromethane solution.     

One-pot Synthesis of 3-Aryl-1,5-bis（2-hydroxyaryl）pentane-1,5-diones

A simple method for the synthesis of 3-aryl-1,5-bis(2-hydroxyaryl)pentane-1,5-diones is developed by one-potreaction involving 2-hydroxyacetophenone and arylaldehyde in aqueous potassium hydroxide.     

Vibrational analysis and solid state conformation of monothiobiuret hydrate

The i.r. assignments for monothiobiuret(Mtb)-hydrate and its deuterated compound have been made from normal coordinate analyses carried out for Mtb and Mtb-d₅ using a chosen molecular model containing a trans-cis —CONHCS— group for Mtb (H₂NCONHCSNH₂). The i.r. spectra of anhydrous Mtb in solid and in solution and of Mtb · H₂O at liquid nitrogen temperature have also been studied.     

Synthesis and solid state conformation of phenylalanine mimetics constrained in a proline-like conformation

We present the synthesis of five- and six-membered cyclic phenylalanine mimics (1, 9, 16 and 17) that are constrained in a proline-like conformation. The five-membered mimetic 16 was prepared by Ring Closing Metathesis (RCM) of diene 15, itself prepared by alpha-benzylation of the L-methionine derived oxazolidinone 10, followed by oxidative elimination, ring hydrolysis and N-allylation. The six-membered mimetic 1 was prepared by allylating the L-phenylalanine-derived oxazolidinone 5, followed by hydrolysis, N-allylation and RCM. Olefins 1 and 16 were catalytically hydrogenated to give 9 and 17, respectively. The solid state structures of 9 and 16 were determined by X-ray crystallography and their conformations compared with that of 1.