Solid state structure of a diazadibenzo-30-crown-10 disulphonamide

X-Ray crystallography of compound (2) has revealed the presence of edge- to-face interactions between N-tosyl groups and catechol residues in symmetry-related molecules in the crystalline state.     

Diazadibenzo-30-crown-10 derivatives as receptors for diquat

In acetone-d6 solution, ¹H n.m.r. spectroscopy reveals that receptors 4–9, prepared from the readily-synthesised diazadibenzo-30-crown-10 derivative 1, form strong 1:1 molecular inclusion complexes with Diquat, which, although present mainly as the dication, is accompanied by trace amounts of the radical cation.     

Complexation of diquat by disubstituted dibenzo-30-crown-10 derivatives

X-Ray structural investigations of the 1:1 crystalline complexes formed between [Diquat][PF₆]₂ and (i) the bisformyl dibenzo-30-crown-10 derivative 2 and (ii) the dimethyl dibenzo-30-crown-10 derivative 4 reveal that in both cases, charge transfer, as well as electrostatic binding and weak [C—···O] hydrogen bonding combine to give the cortlexes their remarkable stabilities; in acetone solution, the stability constants for the 1:1 complexes involving 2, 3, and 4 are 2100, 50000, and 48000 M^-1, respectively.     

Crystal structure of the complex of dibenzo-30-crown-10 with dysprosium isothiocyanate

Crystalline [Dy(NCS)₃(dibenzo-30-crown-10)(H₂O)₂]·H₂O·MeCN can be obtained by slowly evaporating a reaction mixture of Dy(NCS)₃·nH₂O with dibenzo-30-crown-10 in a solution of acetonitrile. The material crystallizes in the monoclinic space groupP2₁/n, the cell parameters area=11.450(5),b=23.284(4),c=18.424(6)Å, =106.28(4)°,V=4715ų,M=968.47,D _x=1.36 g cm^–1, =17.80 cm^–1,F(000)=1972,Z=4.2740 independently observed [I3I] reflections were used in the final least-squares refinement leading to an agreement index ofR=0.085. The Dy(III) ion coordination geometry approximates a square antiprism, involving two water oxygens and three dibenzo-30-crown-10 oxygen atoms and three isthiocyanate nitrogens. Hydrogen bonds are formed between the two water molecules and four uncoordinated crown ether oxygen atoms. Supplementary Data relevant to this paper have been deposited with the British Library as Supplementary Publication No. SUP 82148 (22 pp.)     

Solid state structure of a rhenium bibenzimidazole complex

Re(CO)₅Br readily forms a complex with 2,2′-bibenzimidazole (bbimH₂) of the general composition (bbimH₂)Re(CO)₃Br, 1. The complex was characterized by NMR, IR, electronic and emission spectroscopy. The orange-brown compound is sparingly soluble in apolar solvents but could be crystallized from a DMF/toluene mixture. An X-ray structural investigation shows that the rhenium ion has a distorted octahedral geometry. Nitrogen atoms of the bibenzimidazole are trans to two carbonyl ligands. The secondary amine protons of the bibenzimidazole ligand form a hydrogen bond to the amide oxygen of a DMF molecule; N3–O4 2.725(7)?Å, N4–O4 2.761(7)?Å. The bending angle of the two benzimidazole units is 168°; the greatest deviation from planarity within the ligand is 0.14?Å. Crystal data: monoclinic, space group P2₁/n, a?=?10.9743(2), b?=?12.9182(2), c?=?15.1864(3)?Å, β?=?91.647(1)°, V?=?2152.06(7)?ų, T?=??90°C, Z?=?4, R ₁?=?0.025, wR ₂?=?0.062 for 4296 reflections with F _o?> 4σ(F _o) out of 4886 independent reflections.     

Syntheses of cis- and trans-dibenzo-30-crown-10 derivatives via regioselective routes and their complexations with paraquat and diquat

cis-Dibenzo-30-crown-10 (cis-DB30C10) diester and trans-dibenzo-30-crown-10 (trans-DB30C10) diester were synthesized regioselectively with reasonable yields. These two isomers were further reduced to cis-dibenzo-30-crown-10 diol (1) and trans-DB30C10 diol (2), respectively. The complexations of cis- and trans-DB30C10 diols with paraquat (3) and diquat (4) were investigated by (1)H NMR, mass spectrometry, UV-vis spectroscopy, and single-crystal X-ray analysis. The reversible control of complexations of 1 x 3 and 2 x 3 by adding small molecules (KPF 6 and dibenzo-18-crown-6) was demonstrated by (1)H NMR. The addition of 2 molar equiv of KPF 6 is enough to dissociate 2 x 3 and 1 x 3 completely while the subsequent addition of 2 molar equiv of DB18C6 allows the two complexes to reform. However, 2 molar equiv of KPF6 cannot dissociate 1 x 4 and 2 x 4 completely. Because the DB30C10 cavity has a better geometry fit with paraquat 3 than with diquat 4, 4-based complexes have much higher association constants than the corresponding 3-based complexes. In the crystal structure of 1 x 4, the two hydroxymethyl groups of the crown ether 1 were joined by a "water bridge" to form a "supramolecular cryptand" while this kind of supramolecular cryptand structure was not observed in the crystal structure of 2 x 4. This is a possible reason for the increase in association constant from 2 x 4 (3.3 x 10(4) M(-1)) to 1 x 4 (5.0 x 10(4) M(-1)).     

Solid state of a new flavonoid derivative DA-6034

DA-6034 is a new synthetic flavonoid known to possess anti-inflammatory activity. The objective of this work was to investigate the existence of polymorphs and pseudopolymorphs of DA-6034. Six crystal forms, one hydrate form and five solvates, of DA-6034 have been isolated by recrystallization and characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TG), and powder X-ray diffractometry (PXRD). From the DSC and TG data it was confirmed that Form 1 is monohydrate; Form 2 is DMSO solvate; Form 3 is 1/2 DMSO solvate; Form 4 is 1/2 methyl ethyl ketone solvate; Form 5 is 1.5 H₂O, 1/2 acetic acid solvate; Form 6 is 1/2 H₂O, 1/4 butanol solvate. The PXRD patterns of the six crystal forms were different respectively. In the dissolution studies in pH 6.8 ± 0.05 buffer at 37 ± 0.5 °C, the solubility of solvates was higher than that of Form 1.     

An investigation by high resolution H NMR spectroscopy of the kinetic stabilities of solution complexes of diquat with disubstituted dibenzo-30-crown-10 derivatives

Dynamic ¹ n.m.r. spectroscopy reveals that the disubstituted derivatives 2 - 4 of dibenzo-30-crown-10 (5) form strong 1:1 complexes in CD₃COCD₃ solution with the diquat dication. Desymmetrisation of the guest by the bound host provides the key to a novel application of this form of spectroscopic analysis to molecular receptor chemistry.     

The isolation and X-ray structure of a complex between lithium picrate and dibenzo-36-crown-12

The crystal structure of 2Li picrate.dibenzo-36-crown-12.2H₂O was determined by X-ray diffraction methods. The 2:1 (metal:ligand) complex crystalli     

Crystal structure of the 1:2 molecular complex between thecis-anti-cis isomer of dicyclohexano-18-crown-6 and 3-chloro-6-methylbenzenesulphamide

Reaction of thecis-anti-cis isomer of dicyclohexano-18-crown-6 with a mixture of 2-chloro-5-methylbenzenesulphamide and 3-chloro-6-methylbenzenesulphamide gives a crystalline product which has been characterized using X-ray crystallography. The complex (I) contains both isomers in a 83.0 (0.6):17.0 (0.6) ratio in favour of the 3-chloro-6-methyl-isomer. The joint crystallization of the crown ether with the mixture of the guest isomers might serve as a route for the partial extraction of one of them. The complex with host: guest ratio 1:2 crystallizes in a triclinic space group ,a=13.087(4),b=9.217(2),c=8.120(2) Å, =92.05(3),=100.52(3), =80.64(2)°, withZ=1. The structure was refined toR=0.041. Each of two equivalent guest molecules interacts with the macrocyclic ring by two NH...O hydrogen bonds, with N...O distances of 2.912(5) and 3.040(5) Å. Supplementary Data relevant to this paper have been deposited with the British Libary as Supplementary Publication No. SUP 82180 (30 pp.).     

The isolation and x-ray crystal structure of a complex between sodium hexafluorophosphate and dibenzo-36-crown-12

The crystal structure of 2NaPF₆·dibenzo-36-crown-12 was determined by X-ray diffraction methods. The 2:1 (metal:ligand) complex crystallises in the monoclinic system, space group P2₁/n with cell constants of a = 14.189(2), b = 9.372(1), c = 16.750(3) Å, and β = 108.98(1)°. The two NaPF₆ units are each coordinated through five oxygen atoms to opposite faces of the macrocycle in a centrosymmetric manner.     

Crystal and molecular structure of a 1:1 complex of a chiral α-d-glucosido-benzo-18-crown-6 and potassium thiocyanate

C₂₈H₃₆O₁₀. KSCN is monoclinic, space groupP2₁ withZ=2,a=10.390(3),b=8.959(7),c=16.377(7) Å, =92.49(5)°. FinalR=0.053 for 1437 reflections measured at room temperature. The K^– ion lies on the least-squares plane formed by the six oxygen atoms in the macrocyclic ring. The SCN^– ion was found on the same face of the macrocycle as the chiral glucopyranoside moiety.Methyl-4,6-O-benzylidene-2,3-O-(1,2-bis(ethoxyethoxy)benzenediyl)--d-glucopyranoside.     

Synthesis of an octamethyl-18-crown-6 derivative and the X-ray crystal structure of its 2:1 complex with borane-ammonia

The synthesis of 2,2,3,3,11,11,12,12-octamethyl-1,4,7,10,13,16-hexaoxacyclooctadecane (2) from pinacol (3) by a sequence of reactions (3→4→5→6+5→2) involving alkylation (3→ 4), ozonolysis and reduction (4→5), tosylation (5→6), and cyclisation (5+6→2) is reported. With borane-ammonia, the octamethyl-18-crown-6 derivative 2 forms a crystalline 2:1 complex, (BH₃NH₃)₂ · 2. X-Ray crystallography reveals the two guest BH₃NH₃ molecules are hydrogen bonded in a centrosymmetric manner to the opposite faces of the host 2, which adopts an all-gauche (ag⁺a ag^-a)₃ conformation.     

Crystal and molecular structure of benzoaza-12-crown-4 hydrochloride

Journal of Structural Chemistry - The X-ray crystallographic analysis of benzoaza-12-crown-4 hydrochloride crystals is performed for the first time: space group P1, a = 7.7497(4) Å, b =...     

A bis(m-phenylene)-32-crown-10-based fluorescence chemosensor for paraquat and diquat

A bis(m-phenylene)-32-crown-10-based host to which are covalently attached two pyrene groups as fluorescence chromophores was designed and synthesized. Its complexations with paraquat (PQ) and diquat (DQ) were studied by proton NMR, ESI mass spectrometry, and UV-vis spectroscopy. Its chemosensor behavior to PQ and DQ was revealed by fluorescence emission spectroscopy. This new host can function as a fluorescence chemosensor for PQ and DQ due to the inhibition of photoinduced electron transfer between the bis(m-phenylene)-32-crown-10 moiety and the pyrene groups by the addition of PQ (or DQ).     

The structure of the uncharged-molecule complex between a dinaphthopyridino-18-crown-6 host and acetonitrile (1 : 2)

Single crystal X-ray analysis of a 1 : 2 complex between the dinaphthopyridino-l8-crown-6 host (1) and acetonitrile is reported. Crystals of the complex are monoclinic,P2₁/c witha = 12.178(5),b = 8.186(1),c = 30.873(1) Å, = 96.86(1)°, andD _c = 1.25 g cm^–3 forZ = 4. The host molecule reveals an approximate mirror symmetry and exists in a so-called dentist's chair conformation. One of the acetonitrile guest molecules is involved in possible weak interactions to two oxygen atoms of the host macroring, while the other fills free lattice space only.     

Crystal and molecular structure of a 1:1 complex of potassium perchlorotriphenylmethide and 18-crown-6 (1,4,7,10,13,16-hexaoxacyclooctadecane)

(C₆Cl₅)₃ C^– K⁺, C₁₂H₂₄O₆ is monoclinic, space groupP2₁ withZ=2,a=10.491(2),b=18.016(7),c=11.670(6) , =103.11(3)°,V=2148(1) ³, finalR=0.039 for 2339 observed reflections at room temperature. The overall shape of the perchlorotriphenyl free radical is given by the angles between the mean planes of each ring (around 70°). The K⁺ ion lies at the centre of the 18-membered macrocyclic ring. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. 82012 (19 pages).     

Supramolecular AA-BB-type linear polymers with relatively high molecular weights via the self-assembly of bis(m-phenylene)-32-crown-10 cryptands and a bisparaquat derivative

Two novel bis(m-phenylene)-32-crown-10-based cryptands, one bearing covalent linkages and the other metal-complex linkages, were designed and prepared. By self-assembly of these biscryptands, which can be viewed as AA monomers, and a bisparaquat, which can be viewed as a BB monomer, AA-BB-type linear supramolecular polymers with relatively high molecular weights were successfully prepared.     

Solid state structure and solution conformation of a macrobicyclic cyclophane

X-ray crystallographic structure determination of the macrobicyclic cyclophane L¹ reveals a compact structure involving close edge-to-face approach of aromatic rings; ¹H nmr shows that this is also the solution conformation.     

Elaboration of a chiral 20-crown-6 from a glucofuranose derivative and its complex formation with alkali cations

The synthesis of bis-(1,2-O-isopropylidene-6-O-triphenylmethyl-α-D-glucofuranosyl)-20-crown-6 ( 1 ) and its complexing ability with alkali and ammonium cations are described. The crown ether 1 was synthesized in a stepwise manner via the “half-crown” ( 2 ) using a blocking-deblocking procedure, in which the 3,3′-bridge was formed, followed after suitable manipulations, by formation of the 5,5′-bridge. An unusual feature of the complexing ability of the crown ether is that, although potassium and ammonium ions most closely approach the size of the complexing cavity, it is the sodium ion which forms the most stable complex. Compound 1 does not show chiral recognition toward two alkylammonium salts.