Reaction of Ph2C(X)(CO2H) (X = OH, NH2) with [VO(OR)3] (R = Et, nPr): structure, magnetic susceptibility and ROP capability.

Reaction of [VO(OR)3] (R = Et, nPr) with 2,2'-diphenylglycine afforded the alkoxide-bridged dimers {[VO(OR)(µ-OR)][Ph2C(NH2)(CO2)]}2, whereas use of benzilic acid, in the presence of alkali metals, afforded 16-membered metallocycles {V8(O)4M(OR)8[Ph2C(OH)(CO2)]12} (M = <1 Na, K). For the ring systems, magnetic susceptibility data is consistent with mixed-valence vanadium with an average oxidation state of 3.5. The dimer and ring systems are capable of the ring opening polymerisation (ROP) of ε-caprolactone under N2, air, or as melts affording mostly low to medium molecular weight cyclic and linear products.

Mixed-magnesium/zinc calix[4]arene complexes: structure, and ring opening polymerisation studies.

Different combinations of organomagnesium reagents and zinc bromide react with either 1,3-dimethoxy-4-tert-butylcalix[4]areneH2 (L(OMe)2H2) or trialkoxycalix[4]arenes (L(OR)3H) (R = n-Pr, n-pentyl) to afford mixed-metal calix[4]arene systems. Intriguing molecular structures are formed and the systems are capable of the ring opening polymerisation of ε-caprolactone under N2, air, or as melts.

Trinuclear zinc calix[4]arenes: synthesis, structure, and ring opening polymerization studies.

The trinuclear zinc calix[4]arene complexes [Zn3(O2CCH3)2(L(O)2(OMe)2)2·xMeCN (x = 7.5, 1; x = 6, 1'), [Zn3(O2CCH3)2(L(O)2(OnPr)2)2·5MeCN (2·5MeCN), [Zn3(OEt)2(L(O)2(OMe)2)2]·4MeCN (3·4MeCN), [Zn3(OEt)2(L(Opentyl)2)2]·4.5MeCN (4·4.5MeCN) and [Zn3(OH)2(L(O)2(On-pentyl)2]·8MeCN (5·8MeCN) have been isolated from reaction of [(ZnEt)2(L(O)2(OR)2)2] (L(OH)2(OR)2 = 1,3-dialkoxy-4-tert-butylcalix[4]arene; R = methyl, n-propyl or pentyl) and the reagents acetic acid, ethanol, and presumed adventitious water, respectively. Attempts to make 5via a controlled hydrolysis led only to the isolation of polymorphs of (L(OH)2(Opentyl)2·MeCN. Reaction of [Zn(C6F5)2] with L(OH)2(Opentyl)2, in the presence of K2CO3, led to the isolation of the complex [Zn6(L(On-pentyl))2(OH)3(C6F5)3(NCMe)3]·3MeCN (6·3MeCN). The molecular structures of 1-6 reveal they all contain a near linear (163 to 179°) Zn3 motif. In 1-5, a central tetrahedral Zn centre is flanked by trigonal bipyramidal Zn centres, whilst in 6, for the linear Zn3 unit, a central distorted octahedral zinc centre is flanked by trigonal planar and a tetrahedral zinc centres. Screening for the ring opening polymerization (ROP) of ε-caprolactone at 90 °C revealed that they are active with moderate to good conversion affording low to medium molecular weight products with at least two series of ions. For comparative studies, the trinuclear aminebis(phenolate) complex [Zn3(Oi-Pr)2L/] (L/ = n-propylamine-N,N-bis(2-methylene-4,6-di-tert-butylphenolate) I was prepared. Kinetics revealed the rate order I > 4 > 6 ≈ 2 ≈ 1 > 3.

Vanadyl sulfates: molecular structure, magnetism and electrochemical activity.

Reaction of differing amounts of vanadyl sulfate with p-tert-butylthiacalix[4]areneH4 and base allows access to the vanadyl-sulfate species [NEt4]4[(VO)4(µ3-OH)4(SO4)4]·½H2O (1), [HNEt3]5[(VO)5(µ3-O)4(SO4)4]·4MeCN (2·4MeCN) and [NEt4]2[(VO)6(O)2(SO4)4(OMe)(OH2)]·MeCN (3·MeCN). Similar use of p-tert-butylsulfonylcalix[4]areneH4, p-tert-butylcalix[8]areneH8 or p-tert-butylhexahomotrioxacalix[3]areneH3 led to the isolation of [HNEt3]2[H2NEt2]2{[VO(OMe)]2p-tert-butylcalix[8-SO2]areneH2} (4), [HNEt3]2[V(O)2p-tert-butylcalix[8]areneH5] (5) and [HNEt3]2[VIV2VV4O11(OMe)8] (6), respectively. Dc magnetic susceptibility measurements were performed on powdered microcrystalline samples of 1-3 in the T = 300-2 K temperature range. Preliminary screening for electrochemical water oxidation revealed some activity for 2 with turnover frequency (TOF) and number (TON) of 2.2 × 10-4 s-1 and 6.44 × 10-6 (mmol O2/mmol cat.), respectively. The compound 3 showed an improved electrochemical activity in the presence of water. This is related to the increased number and the rate of electrons exchanged during oxidation of V4+ species, facilitated by protons generated in the water discharge process.

Vanadyl complexes bearing bi-dentate phenoxyimine ligands: synthesis, structural studies and ethylene polymerization capability.

Reaction of [VO(OnPr)3] with the Schiff bases 3,5-(tBu)2-2-OH-C6H2CH(N(x-OR-C6H4)) (R = Me; x = 2, L(1)H; x = 3, L(2)H; x = 4, L(3)H; R = Et (L(4)H), CF3 (L(5)H), Ph (L(6)H)) or 4-methyl-3-(R)-2-(OH)-C6H4C[double bond, length as m-dash]N(2'-(2''-(OR1)C6H4)C6H4) (R = adamantyl, R(1) = Ph (L(7)H) or R = C(Me)2Ph, R(1) = Ph (L(8)H)) afforded the bis(chelate) vanadium(iv) complexes [VO(L(n))2] (n = 1 (1·2MeCN); n = 2 (2); n = 3 (3·2MeCN); n = 4 (4); n = 5 (5); n = 6 (6); n = 6, (7·1.5MeCN); n = 7, (8); n = 8, (9)); in the case of L(6)H, the oxo-bridged vanadium(v) complexes [VO(µ-O)(L(6))]2 (10) was also isolated. By contrast, interaction of 4-methyl-3-(R)-2-(OH)-C6H4C[double bond, length as m-dash]N(2'-(2''-(OR1)C6H4)C6H4) (R = adamantyl, R(1) = Me (L(9)H); R = tBu, R(1) = Me (L(10)H); R = C(Me)2Ph, R(1) = Me (L(11)H)) with [VO(OnPr)3] led to the isolation of the dinuclear complexes [VO(µ-OH)(µ-OnPr)(L(n))]2 (n = 9, (·4MeCN); 10, (12); 11, (13)), respectively. The molecular structures of 1 to 13 are reported. All complexes have been screened as pre-catalysts for the polymerization of ethylene in the presence of the co-catalyst diethylaluminium chloride (DEAC) with or without ethyltrichloroacetate (ETA) present at 1 or 10 bar of ethylene. Under high pressure, all pre-catalysts exhibited high activity and afforded high molecular weight (Mw ≈ 200 000 to 675 000 g mol(-1)), linear polyethylene with activities (in the presence of ETA) in the range 4960-16 400 g mmol(-1) h(-1); at one bar, the products were generally of lower molecular weight. The use of methylaluminoxane (MAO) or modified MAO (MMAO) as co-catalyst led to trace or poor (≤110 g mmol(-1) h(-1)) activity, respectively.

Cellular uptake studies of two hexanuclear, carboxylate bridged, zinc ring structures using fluorescence microscopy.

Two hexanuclear zinc complexes have been structurally characterized, and evaluation against several cells showed selective toxicity. Cellular uptake revealed a non-specific process, resulting in accumulation within the cell cytoplasm.

7-[2-(3-Fur-yl)eth-yl]-7,8-dimethyl-3,5,6,6a,7,8,9,10-octa-hydro-1H-naphtho-[1,8a-c]furan-3-one.

In the title mol-ecule, C(20)H(26)O(3), a clerodane diterpenoid isolated from Dodonaea viscosa-, the trans-fused six-membered rings of the deca-line system display chair conformations. The five-membered lactone ring adopts an envelope conformation and the five-membered furan ring is essentially planar with a maximum deviation of 0.0052 (12) Å.

5,7-Dihy-droxy-3,6-dimeth-oxy-2-(4-meth-oxy-phen-yl)-4H-chromen-4-one monohydrate.

The title compound, C(18)H(16)O(7)·H(2)O, is a flavonoid isolated from Dodonaea viscosa-. The benzopyran ring system of the flavonoid is essentially planar [maximum deviation = 0.025 (2) Å] and inclined at 5.83 (2)° to the attached benzene ring. The water of hydration is involved in extensive hydrogen bonding, assembling the mol-ecules into a supra-molecular network via classical inter-molecular O-H⋯O hydrogen bonding. The crystal structure is further stabilized by π-π stacking inter-actions [centroid-centroid distance between benzene rings = 3.564 (3) Å].