Comparison of the electronic absorption spectra of the isomeric 1,1′- and 2,2′-binaphthyl spiro [cyclophosphazene] derivatives

It has been found that the u.v.-spectrum of the monospiro [(2,2′-dioxybinaphthyl-1,1′) cyclophosphazene] (3) closely resembles those of the other previously described 7-membered 2,2′-bridged 1,1′-binaphthyl derivatives. An hitherto unreported effect of the associated influence of α-substitution, β-coupling and the next cyclization on the u.v. absorption of naphthalene chromophore has been shown by the comparison of the electronic spectra of 1-naphthol (5), 1,1′-dihydroxybinaphthyl-2,2′ (6) and monospiro [(1,1′-dioxybinaphthyl-2,2′) cyclophosphazene] (7). Exclusively strong resonance interaction between the conjugated naphthalene rings was evidenced for 7.     

A highly efficient method for the resolution of 8,8′-dihydroxy-1,1′-binaphthyl

The diastereomeric mixture of monoesters of racemic 8,8′-dihydroxy-1,1′-binaphthyl and N-CBZ-l-proline was easily separated. Each diastereomer gave enantiomerically pure (R)- or (S)-8,8′-dihydroxy-1,1′-binaphthyl in good yields after hydrolysis.     

Molecular recognition and supramolecular self-assemblies of (±)-2,2′-dihydroxy-1,1′-binaphthyl with aromatic aza compounds

Abstract  (±)-2,2′-dihydroxy-1,1′-binaphthyl (binol) co-crystallized with 1,10-phenanthroline-5,6-dione and acridine to afford co-crystals (Binol)·(1,10-phenanthroline-5,6-dione) 1 and (Binol)·(acridine)₂ 2, respectively. Co-crystal 1 crystallizes in space group P-42(1)c, with a = 14.9921(4), b = 14.9921(4), c = 20.8102(12) ?. Co-crystal 2 crystallizes in space group P2/c, with a = 17.8004(19), b = 10.0093(11), c = 19.393(2) ?, and α = γ = 90°, β = 103.187(2)°. In co-crystal 1, the components form an infinite 1D polar array; whereas in 2, the components form discrete three-component aggregates. Graphical abstract   Molecular recognition and supramolecular self-assemblies of (±)-2,2′-dihydroxy-1,1′-binaphthyl with aromatic aza compounds Baoming Ji, Shaobin Miao, Dongsheng Deng As a result of mutual recognition, (±)-binol with 1,10-phenanthroline-5,6-dione and acridine afforded co-crystals 1 and 2, respectively. In 1 the components form an infinite 1D polar array, whereas in 2 the components form discrete three-component aggregates.      

Studies of hydrogen bonding—XXVII. NMR studies of hydrogen bonding and solvent effect

The OH proton chemical shifts are reported of dilution study of 2-methyl-6-t-butylphenol (2M6TBP) and 2,6-di-t-butylphenol (2.6DTBP), and of the 1:1 association between the phenols and hexamethylphosphoramide (HMPA) in C₆H₁₂, CCl₄, CH₃NO₂, CH₃CN and C₆H₆ at 25, 35 and 50°C. Also the association of the phenols with CH₃NO₂, CH₃CN and CCl₄ has been studied. The phenol OH chemical shift, δ_f, found by extrapolation to zero concentration, shows the highest upfield shift in benzene. Contrary, on adding HMPA, the complex OH chemical shift, δ_x, shows the lowest downfield shift in benzene.The K_ass, δ_x, ΔH and ΔS values have been evaluated by using the Hiquchi plot method. Linear relationships were obtained between Δδ_x and ΔH, and log K_ass for the system 2M6TBP/HMPA in the various solvents. Furthermore, the difference in H-bond energy of a given system in an inert solvent (C₆H₁₂) and in aprotic solvent (CH₃CN), corresponds to the enthalpy of association of the given donor with CH₃CN in C₆H₁₂.The K_ass value for the system 2M6TBP/HMPA is 10 times greater in C₆H₁₂ than in C₆H₆ and CCl₄, 100 times than in CH₃NO₂ and 300 times than in CH₃CN.     

A New and Efficient Method for the Synthesis of 2,2′-Dibromo-1,1′-binaphthyl Under Microwave Irradiation

Abstract

A very simple and efficient method to prepare 2,2′-dibromo-1,1′-binaphthyl via two-step procedure from β-naphthol in good yield under microwave irradiation is described.     

A Practical Procedure for the Solid-Phase Synthesis of Racemic 2,2′-Dihydroxy-1,1′-binaphthyl

Abstract: A high yielding solid-phase dimerisation of 2-naphthol by means of a ball-milling procedure is described.

     

Structures of the crystalline supramolecular associates of imidazole with 1,1′-binaphthyl-8,8′-dicarboxylic acid and 2,2′-dihydroxy-1,1′-binaphthyl. Spatial similarity of the acid associate crystal packing to the active site of a serine protease

Abstract

Crystal structure analysis of the imidazole associates with 1,1′-binaphthyl-8,8′-dicarboxylic acid (1), [1a, triclinic, P1, a = 7.569(4), b = 8.393(2), c = 8.634(1) Å, α = 93.21(2), β = 106.88(3), γ = 105.17(3)°, D_c = 1.36 g/cm³, Z = 1, R = 0.045 for 1031 data] and with 2,2′-dihydroxy-1,1′-binaphthyl (2), [2a, tetragonal P4₁2₁2, a = 8.519(1), c = 29.821(2), D_c = 1.30 g/cm³, Z = 4, R = 0.051 for 1236 reflections] revealed 1:1 and 1:2 stoichiometry, respectively. Spontaneous resolution occur during crystallization in both compound crystals. 1a is a salt-like associate with hydrogen bonds between the carboxylate and imidazolium ion pairs while the neutral 2a has also well defined hydrogen bonds between host and guest molecules. In a modeling experiment corresponding Brookhaven Protein Data Bank atomic coordinates from the active site of the bacterial serine protease enzyme Subtilisin BPN were fitted to the crystal packing of the small molecule associate 1a crystal. The relative displacement of the ion pair components and a symmetry related carboxyl function in 1a has fair steric resemblance to similar moieties in the active site of Subtilisin (Δ_ave = 0.24 Å for 9 fitted atoms). The agreement in the results of two fully independent and totally different (i.e. a native protein active site and an artificial small molecule associate) crystal structure determinations underlines the assumed conceptual similarity of crystals (“giant supramolecules”) to protein sequences optimized through evolution.     

Spectroscopic study of hydrogen bonding in the enol form of β-diketones—I. Vibrational assignment and strength of the bond

The i.r. and Raman spectra of the trans-enol form of some β-diketones and their deuterated analogues in α position are examined in the 4000-50cm⁻¹ range and an approximate assignment is given for the fundamental vibrations. The ν_as(OH) and ν(CO) values suggest that the intramolecular H-bond strength increases in the order: hexafluoroacetylacetone < trifluoroacetylacetone < acetylacetone < α - Cl - acetylacetone < benzoylacetone < dibenzoylmethane < tetraacetylethane.The observed relative Raman intensities of the ν(CC) and ν(CC) bands also support this feature. The spectroscopic results show a great change in the internal modes of the β-diketones upon deuteration; this behaviour indicates a greater localization of the π-electron system of the chelate ring and a weakening of the H-bond on deuteration. The ν_s(OH) vibration seems to be involved in one of the in-plane ring deformational modes.     

Synthesis of 1,1′-Dibenzo- and 1,1′-Dinaphtho-2,2′-Dithiols from the Respective Thiophenes

The title compounds 1 and 2 were prepared from the respective, inexpensive and readily available thiophenes via reaction with lithium and sulfur monochloride, followed by reduction with lithium aluminium hydride.     

Spectroscopic study of hydrogen bonding in the enol form of β-diketones—II. Symmetry of the hydrogen bond

The effects of proton potential on the i.r. and Raman spectra of β-diketones are discussed. The spectroscopic behaviour of the asymmetric hydrogen bond stretching mode and of the out-of-plane hydrogen bond bending modes indicates a relatively high barrier double minimum potential.From the observed O…O distances and these predicted from the spectroscopic results for intermolecular H-bonds, a bent hydrogen bond was concluded. The spectroscopic data show a great change in the internal modes of β-diketones upon deuteration. This was attributed to the lengthening of the O…O distance which is a known characteristic of a double minimum potential.     

Infrared study of hydrogen bonds involving 2,2′-bipyridine and 2,2′-bipyrimidine. Influence of equivalent nitrogen atoms on the hydrogen bond strength

Hydrogen bonding between proton donors (phenols and water) and 2,2′-bipyridine (BPR) or 2,2′-bipyrimidine (BPM) has been investigated by infrared and FT-infrared techniques. The thermodynamic parameters (K, - ΔH, - ΔS°) and the frequency shifts of the ν_OH stretching vibrations have been determined in carbon tetrachloride solution. The spectroscopic results suggest that the complexes formed between phenols covering a large pK_a range (10.3–3.50) and BPR or BPM are of the normal OH⋯N type. The thermodynamic and spectroscopic properties of the BPR and BPM complexes are compared with those previously reported for the interaction between the same proton donors and the model molecules pyridine and pyrimidine. The BPR and pyridine complexes belong to the same series. The behaviours of BPM and pyrimidine are in complete contrast, the thermodynamic parameters and the related proton affinity being much higher for BPM than for pyrimidine. The results are probably ascribable to the presence of two equivalent neighbouring nitrogen atoms, the approach of a hydroxylic proton donor being greatly favoured in this electron-rich region. This effect does not exist in BPR, owing to its transoid configuration in solvents of weak polarity.     

Spectroscopic and structural studies of 6,6′-bis(N-methylhydrazine)-2,2′-bipyridine and its mononuclear copper(II) complex

The tetradentate ligand, 6,6′-bis(N-methylhydrazine)-2,2′-bipyridine (L) and its mononuclear copper(II) complex [Cu(L)](ClO₄)₂] (1) have been synthesized and characterized. The crystal structures of L and 1 have been determined by single-crystal X-ray diffraction. Both crystallize in the centrosymmetric monoclinic space group with crystallographic inversion symmetry. The ligand adopts a planar transoid configuration in the solid state. In 1, the Cu(II) is six-coordinate octahedral, defined by N₄O₂ donors from ligand and two perchlorates. The molecular units are connected by intermolecular H-bonds between the hydrazino group of the one unit and coordinated perchlorate of the neighboring two units via N–H ··· O to furnish a 2-D network. Coordinated perchlorates also form an intramolecular H-bond with hydrazine influencing the crystal packing.     

Comparative study of the electrosynthesis and characterization of films made from 1,1′-binaphthyl and 2-methoxynaphthalene

Oligomers of 2-methoxynaphthalene and 1,1-binaphthyl were electrochemically synthesized by cyclic voltammetry (CV) in 0.1 M tetrabutylammonium hexafluorophosphate–nitrobenzene (TBAPF₆–NB). The redox characterization of the films was studied in monomer-free 0.1 M TBAPF₆–NB and 0.1 M tetrabutylammonium hexafluorophosphate–acetonitrile (TBAPF₆–ACN) solutions. The electrochemical response from the anodic charging (p-doping) of an oligo(1,1-binaphthyl) film in both solvents consists of a continously increasing current without a well-defined oxidation peak. Upon discharging the film a distinct reduction peak can be seen. The p-doping response of an oligo(2-methoxynaphthalene) film in both solvents consists of a prepeak followed by a plateau until the new electrochemical process starts. On the reverse scan two poorly resolved reduction peaks which merge into a broad cathodic peak as the scan rate increases can be observed. The cathodic charging and discharging (n-doping) response of 2-methoxynaphthalene film in 0.1 M TBAPF₆–ACN consists of a broad and well-defined redox peak. The structures of the film were studied by Raman and Fourier transform infrared spectroscopy (FTIR). Both techniques provide complementary vibrational information on the coupling of the starting materials studied. The morphologies of the electrosynthesized films were studied by scanning electron microscopy (SEM). The influence of the two substituents, the methoxy and naphthyl groups, on the electrosynthesis properties of the naphthalene molecule was studied.     

On the use of seven-membered phosphorous heterocycles based on 2,2′-dihydroxy-1,1′-binaphthalene and 1,4∶3,6-dianhydro-d-mannitol in the31P NMR analysis of the enantiomeric composition of chiral alcohols

Some aspects of phosphorylation of 2,2′-dihydroxy-1,1′-binaphthalene (BINOL) and 1,4∶3,6-dianhydro-d-mannitol (isomannide) were investigated. The possibility of using the corresponding cyclic chloro- and amidophosphites for the analysis of enantiomeric compositions of chiral primary and secondary alcohols by³¹P NMR was examined. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 426–431, March, 1998.     

2,2′-Dialkoxy, 2,2′-dihydroxy,and 2,2′-diamino derivatives of 1,1′-azobenzimidazole. The first synthesis of heterocyclic tetrazenes by means of a nucleophilic substitution reaction

2,2-Dimethanesulfonyl-1,1-azobenzimidazole is prepared by the oxidation of 1-amino-2-methanesulfonylbenzimidazole with lead tetraacetate. The reaction of this tetrazene with alkali in DMSO, with sodium alkoxides in the corresponding alcohol or ammonia, or with primary or secondary amines leads to the formation of 2,2-dihydroxy, 2,2-dialkoxy, or 2,2-diamino derivatives of 1,1-azobenzimidazole.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 190–193, February, 1992.     

Spectroscopic characterizations on the N,N′-bis-alkyl derivatives of 1,4,6,8-naphthalenediimide charge-transfer complexes

Charge-transfer (CT) complexes formed from the reactions of two N,N′-bis-alkyl derivatives of 1,4,6,8-naphthalenediimide such as N,N′-bis-[2-hydroxyethyl]-1,4,6,8-naphthalenediimide (BHENDI) and N,N′-bis-[2-N,N-dimethylaminoethyl]-1,4,6,8-naphthalenediimide (BDMAE NDI) with DDQ, CHL, TCNQ, DCQ and DBQ as π-acceptors have been studied spectrophotometrically in chloroform and/or methanol at 25 °C. The photometric titration curves for the reactions indicated that the data obtained refer to 1:1 charge-transfer complexes of [(BHENDI)(DDQ)], [(BDMAENDI)(DDQ)], [(BHENDI)(CHL)], [(BDMAENDI)(CHL)], [(BHENDI)(TCNQ)], [(BDMAENDI)(TCNQ)], [(BHENDI)(DCQ)], [(BDMAENDI)(DCQ)], [(BHENDI)(DBQ)] and [(BDMAENDI)(DBQ)] were formed. Benesi–Hildebrand and its modification methods were applied to the determination of association constant (K), molar extinction coefficient (?). The solid CT complexes have been synthesized and characterization by different spectral methods.     

Role of the transition metal complexes of 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl (BINAP) in asymmetric catalysis

Metal complexes of 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl (BINAP) are being used as a chiral catalysts in many organic reactions. This review highlights recent developments on synthesis of metal BINAPs and its application in various organic synthesis. The studies done on the application of metal BINAPs show a unique reactivity, which enables its use in entirely different sets of chemical transformation.