Compressive behaviour of nanocrystallilne Mg-5%Al alloys

Magnesium alloys are attracting increasing research interests due to their low density, high specific strength and good mechineability and availability as compared to other structural materials. However, the deformation and failure mechanisms of nanocrystalline Mg alloys have not been well understood. In this work, the deformation behavior of nanocrystalline Mg-5% Al alloys was investigated using compression test, with a focus on the effects of grain size. The average grain size of the Mg-Al alloy was changed from 13 µm to 50 nm via mechanical milling. The results showed that grain size had a significant influence on the yield stress and ductility of the Mg alloys, and the materials exhibited increased strain rate sensitivity with decrease of grain size. The deformation mechanisms were also strongly dependent with the grain sizes.

Characterization of particle number concentrations and PM2.5 in a school : influence of outdoor air pollution on indoor air

Background, Aim and Scope The impact of air pollution on school children’s health is currently one of the key foci of international and national agencies. Of particular concern are ultrafine particles which are emitted in large quantities, contain large concentrations of toxins and are deposited deeply in the respiratory tract. Materials and methods In this study, an intensive sampling campaign of indoor and outdoor airborne particulate matter was carried out in a primary school in February 2006 to investigate indoor and outdoor particle number (PN) and mass concentrations (PM2.5), and particle size distribution, and to evaluate the influence of outdoor air pollution on the indoor air. Results For outdoor PN and PM2.5, early morning and late afternoon peaks were observed on weekdays, which are consistent with traffic rush hours, indicating the predominant effect of vehicular emissions. However, the temporal variations of outdoor PM2.5 and PN concentrations occasionally showed extremely high peaks, mainly due to human activities such as cigarette smoking and the operation of mower near the sampling site. The indoor PM2.5 level was mainly affected by the outdoor PM2.5 (r = 0.68, p<0.01), whereas the indoor PN concentration had some association with outdoor PN values (r = 0.66, p<0.01) even though the indoor PN concentration was occasionally influenced by indoor sources, such as cooking, cleaning and floor polishing activities. Correlation analysis indicated that the outdoor PM2.5 was inversely correlated with the indoor to outdoor PM2.5 ratio (I/O ratio) (r = -0.49, p<0.01), while the indoor PN had a weak correlation with the I/O ratio for PN (r = 0.34, p<0.01). Discussion and Conclusions The results showed that occupancy did not cause any major changes to the modal structure of particle number and size distribution, even though the I/O ratio was different for different size classes. The I/O curves had a maximum value for particles with diameters of 100 – 400 nm under both occupied and unoccupied scenarios, whereas no significant difference in I/O ratio for PM2.5 was observed between occupied and unoccupied conditions. Inspection of the size-resolved I/O ratios in the preschool centre and the classroom suggested that the I/O ratio in the preschool centre was the highest for accumulation mode particles at 600 nm after school hours, whereas the average I/O ratios of both nucleation mode and accumulation mode particles in the classroom were much lower than those of Aitken mode particles. Recommendations and Perspectives The findings obtained in this study are useful for epidemiological studies to estimate the total personal exposure of children, and to develop appropriate control strategies for minimizing the adverse health effects on school children.

Exposure to ultrafine particles and PM2.5 in four Sydney transport modes

Concentrations of ultrafine (<0.1µm) particles (UFPs) and PM2.5 (<2.5µm) were measured whilst commuting along a similar route by train, bus, ferry and automobile in Sydney, Australia. One trip on each transport mode was undertaken during both morning and evening peak hours throughout a working week, for a total of 40 trips. Analyses comprised one-way ANOVA to compare overall (i.e. all trips combined) geometric mean concentrations of both particle fractions measured across transport modes, and assessment of both the correlation between wind speed and individual trip means of UFPs and PM2.5, and the correlation between the two particle fractions. Overall geometric mean concentrations of UFPs and PM2.5 ranged from 2.8 (train) to 8.4 (bus) × 104 particles cm-3 and 22.6 (automobile) to 29.6 (bus) µg m-3, respectively, and a statistically significant difference (p <0.001) between modes was found for both particle fractions. Individual trip geometric mean concentrations were between 9.7 × 103 (train) and 2.2 × 105 (bus) particles cm-3 and 9.5 (train) to 78.7 (train) µg m-3. Estimated commuter exposures were variable, and the highest return trip mean PM2.5 exposure occurred in the ferry mode, whilst the highest UFP exposure occurred during bus trips. The correlation between fractions was generally poor, and in keeping with the duality of particle mass and number emissions in vehicle-dominated urban areas. Wind speed was negatively correlated with, and a generally poor determinant of, UFP and PM2.5 concentrations, suggesting a more significant role for other factors in determining commuter exposure.

Functional status, postural stability and falls among older adults with glaucoma

Visual impairment is an important contributing factor in falls among older adults, which is one of the leading causes of injury and injury-related death in this population. Visual impairment is also associated with greater disability among older adults, including poorer health-related quality of life, increased frailty and reduced postural stability. The majority of this evidence, however, is based on measures of central visual function, rather than peripheral visual function. As such, there is comparatively limited research on the associations between peripheral visual function, disability and falls, and even fewer studies involving older adults with specific diseases which affect peripheral visual function, the most common of which is glaucoma. Glaucoma is one of the leading causes of irreversible vision loss among older adults, affecting around 3 per cent of adults aged over 60 years. The condition is characterised by retinal nerve fibre loss, primarily affecting peripheral visual function. Importantly, the number of older adults with glaucomatous visual impairment is projected to increase as the ageing population grows. The first component of the thesis examined the cross-sectional association between glaucomatous visual impairment and health-related quality of life (Study 1a), functional status (Study 1b) and postural stability (Study 1c) among older adults. A cohort of 74 community-dwelling adults with glaucoma (mean age 74.2 ± 5.9 years) was recruited and completed a baseline assessment. A number of visual function measures was assessed, including central visual function (visual acuity and contrast sensitivity), motion sensitivity, retinal nerve fibre analysis and monocular and binocular visual field measures (monocular 24-2 and binocular integrated visual fields (IVF): IVF-60 and IVF-120). The analyses focused on the associations between the outcomes measures and severity and location of visual field loss, as this is the primary visual function affected by glaucoma. In Study 1a, we examined the association between visual field loss and health-related quality of life, measured by the Short Form 36-item Health Survey (SF-36). Greater binocular visual field loss, on both IVF measures, was associated with lower SF-36 physical component scores, adjusted for age and gender (Pearson's r =|0.32| to |0.36|, p<0.001). Furthermore, inferior visual field loss was more strongly associated with the SF-36 physical component than superior field loss. No association was found between visual field loss and SF-36 mental component scores. The association between visual field loss and functional status was examined in Study 1b. Functional status outcomes measures included a physical activity questionnaire (Physical Activity Scale for the Elderly, PASE), performance tests (six-minute walk test, timed up and go test and lower leg strength) and an overall functional status score. Significant, but weak, correlations were found between binocular visual field loss and PASE and overall functional status scores, adjusted for age and gender (Pearson's r =|0.24| to |0.33|, p<0.05). Greater inferior visual field loss, independent of superior visual field loss, was significantly associated with poorer physical performance results and lower overall functional status scores. In Study 1c, we examined the association between visual field loss and postural stability, using a swaymeter device which recorded body movement during four conditions: eyes open and closed, on a firm and foam surface. Greater binocular visual field loss was associated with increased postural sway, both on firm and foam surfaces, independent of age and gender (Pearson’s r =|0.44| to |0.46|, p <0.001). Furthermore, inferior visual field was a stronger contributor to postural stability, more so than the superior visual field, particularly on the foam condition with the eyes open. Greater visual field loss was associated with a reduction in the visual contribution to postural sway, which underlies the observed association with postural sway. The second component of the thesis examined the association between severity and location of visual field loss and falls during a 12-month longitudinal follow-up. The number of falls was assessed prospectively using monthly fall calendars. Of the 71 participants who successfully completed the follow up (mean age 73.9 ± 5.7 years), 44% reported one or more falls, and around 20% reported two or more falls. After adjusting for age and gender, every 10 points missed on the IVF-120 increased the rate of falls by 25% (rate ratio 1.25, 95% confidence interval 1.08 - 1.44) or every 5dB reduction in IVF-60 increased the rate of falls by 47% (rate ratio 1.47, 95% confidence interval 1.16 - 1.87). Inferior visual field loss was a significant predictor of falls, more so than superior field loss, highlighting the importance of the inferior visual field area in safe and efficient navigation. Further analyses indicated that postural stability, more so than functional status, may be a potential mediating factor in the relationship between visual field loss and falls. Future research is required to confirm this causal pathway. In addition, the use of topical beta-blocker medications was not associated with an increased rate of falls in this cohort, compared with the use of other topical anti-glaucoma medications. In summary, greater binocular visual field loss among older adults with glaucoma was associated with poorer health-related quality of life in the physical domain, reduced functional status, greater postural instability and higher rates of falling. When the location of visual field loss was examined, inferior visual field loss was consistently more strongly associated with these outcomes than superior visual field loss. Insights gained from this research improve our understanding of the association between glaucomatous visual field loss and disability, and its link with falls among older adults. The clinical implications of this research include the need to include visual field screening in falls risk assessments among older adults and to raise awareness of these findings to eye care practitioners and adults with glaucoma. The findings also assist in developing further research to examine strategies to reduce disability and prevent falls among older adults with glaucoma to promote healthy ageing and independence for these individuals.

Hydrogen bonding in the anhydrous 1:1 proton-transfer compounds of isonipecotamide with nitro-substituted benzoic acids: the salts of the three isomeric mononitrobenzoic acids and of 3,5-dinitrobenzoic acid

The structures of the anhydrous 1:1 proton-transfer compounds of isonipecotamide (piperidine-4-carboxamide) with the three isomeric mononitro-substituted benzoic acids and 3,5-dinitrobenzoic acid, namely 4-carbamoylpiperidinium 2-nitrobenzoate (I), 4-carbamoylpiperidinium 3-nitrobenzoate (II), 4-carbamoylpiperidinium 4-nitrobenzoate (III), (C6H13N2O+ C7H4NO4-) and 4-carbamoylpiperidinium 3,5-dinitrobenzoate (IV) (C6H13N2O+ C7H5N2O6-)respectively, have been determined at 200 K. All salts form hydrogen-bonded structures: three-dimensional in (I), two-dimensional in (II) and (III) and one-dimensional in (IV). Featured in the hydrogen bonding of three of these [(I), (II) and (IV)] is the cyclic head-to-head amide--amide homodimer motif [graph set R2/2~(8)] through a duplex N---H...O association, the dimer then giving structure extension via either piperidinium or amide H-donors and carboxylate-O and in some examples [(II) and (IV)], nitro-O atom acceptors. In (I), the centrosymmetric amide-amide homodimers are expanded laterally through N-H...O hydrogen bonds via cyclic R2/4(8) interactions forming ribbons which extend along the c cell direction. These ribbons incorporate the 2-nitrobenzoate cations through centrosymmetric cyclic piperidine N-H...O(carboxyl) associations [graph set R4/4(12)], giving inter-connected sheets in the three-dimensional structure. In (II) in which no amide-amide homodimer is present, duplex piperidinium N-H...O(amide) hydrogen-bonding homomolecular associations [graph set R2/2(14)] give centrosymmetric head-to-tail dimers. Structure extension occurs through hydrogen-bonding associations between both the amide H-donors and carboxyl and nitro O-acceptors as well as a three-centre piperidinium N-H...O,O'(carboxyl) cyclic R2/1(4) association giving the two-dimensional network structure. In (III), the centrosymmetric amide-amide dimers are linked through the two carboxyl O-atom acceptors of the anions via bridging piperidinium and amide N-H...O,O'...H-N(amide) hydrogen bonds giving the two-dimensional sheet structure which features centrosymmetric cyclic R4/4(12) associations. In (IV), the amide-amide dimer is also centrosymmetric with the dimers linked to the anions through amide N-H...O(nitro) interactions. The piperidinium groups extend the structure into one-dimensional ribbons via N-H...O(carboxyl) hydrogen bonds. The structures reported here further demonstrate the utility of the isonipecotamide cation in molecular assembly and highlight the efficacy of the cyclic R2/2(8) amide-amide hydrogen-bonding homodimer motif in this process and provide an additional homodimer motif type in the head-to-tail R2/2(14) association.

A two-compartment mechanochemical model of the roles of transforming growth factor-beta and tissue tension in dermal wound healing

The repair of dermal tissue is a complex process of interconnected phenomena, where cellular, chemical and mechanical aspects all play a role, both in an autocrine and in a paracrine fashion. Recent experimental results have shown that transforming growth factor-beta (TGF-beta) and tissue mechanics play roles in regulating cell proliferation, differentiation and the production of extracellular materials. We have developed a 1D mathematical model that considers the interaction between the cellular, chemical and mechanical phenomena, allowing the combination of TGF-beta and tissue stress to inform the activation of fibroblasts to myofibroblasts. Additionally, our model incorporates the observed feature of residual stress by considering the changing zero-stress state in the formulation for effective strain. Using this model, we predict that the continued presence of TGF-beta in dermal wounds will produce contractures due to the persistence of myofibroblasts; in contrast, early elimination of TGF-beta significantly reduces the myofibroblast numbers resulting in an increase in wound size. Similar results were obtained by varying the rate at which fibroblasts differentiate to myofibroblasts and by changing the myofibroblast apoptotic rate. Taken together, the implication is that elevated levels of myofibroblasts is the key factor behind wounds healing with excessive contraction, suggesting that clinical strategies which aim to reduce the myofibroblast density may reduce the appearance of contractures.

Contribution of transmembrane domain V amino acids to β1l-adrenoceptor activity and affinity

There are two binding sites on the β1-adrenoceptor (AR), β1H and β1L corresponding to high and low affinity binding sites respectively, which can be activated to cause cardiostimulation (reviewed Kaumann and Molenaar, 2008). Some β-blockers that block β1AR and β2ARs can activate β1LARs at higher concentrations than those required to cause blockade. The β2AR does not form a corresponding low affinity binding site (Baker et al 2002) and therefore we postulated that heterologous amino acids are responsible for the formation of β1LAR. Our aim was to investigate whether heterologous amino acids of transmembrane domain V (TMDV) of β1AR and β2ARs contribute to β1LAR. β1ARs, β2ARs and mutant β1ARs containing all (β1(β2TMDV)AR) or single amino acids of TMDV of the β2AR were prepared and stably expressed in Chinese Hamster Ovary cells. Concentration-effect curves for cyclicAMP accumulation were carried out for (-)-CGP12177 or (-)-isoprenaline in the absence or presence of (-)-bupranolol. _______________________________________________________________________ (-)-CGP 12177 (-)-Bupranolol affinity (pKB) pEC50 vs (-)-CGP 12177 vs (-)-isoprenaline _______________________________________________________________________ β1AR 8.00 ± 0.11 (11) 7.23 ± 0.23 (5) 9.52 ± 0.28 (5) β2AR (high density) 9.24 ± 0.14 (5) 9.82 ± 0.52 (8) xPaulxxxxxxx β2AR (low density) no effect β1(β2TMV)AR 8.86 ± 0.10 (15) 8.06 ± 0.17 (8) 9.08 ± 0.22 (6) β1(V230I)AR 9.07 ± 0.07 (10) 7.64 ± 0.12 (8) 9.36 ± 0.28 (9) β1(R222Q)AR 8.09 ± 0.29 (6) 7.33 ± 0.23 (5) 9.36 ± 0.08 (6) β1(V230A)AR 7.59 ± 0.09 (6) 7.32 ± 0.24 (4) 8.62 ± 0.18 (5) _______________________________________________________________________ The potency of (-)-CGP12177 was higher at β2AR than at β1AR consistent with activation through a low affinity site at the β1AR (β1LAR) but not β2AR. The presence of V230 in β1AR accounted for the lower potency of (-)-CGP 12177. The affinity of (-)-bupranolol at β1AR and mutants was higher when determined with (-)-isoprenaline than with (-)-CGP 12177. The affinity of (-)-bupranolol determined against (-)-CGP 12177 was lower at β1AR compared to β2AR. The presence of V230 in β1AR accounted in part for the lower affinity. In conclusion V230 of the β1AR contributes in part to the low affinity binding site of β1AR. Baker JG, Hall IP, Hill SJ (2002). Pharmacological characterization of CGP12177 at the human β2-adrenoceptor. Br J Pharmacol 137, 400−408 Kaumann AJ, Molenaar P (2008) The low-affinity site of the β1-adrenoceptor and its relevance to cardiovascular pharmacology. Pharmacol Ther 118, 303-336

Dussertite BaFe3+3(AsO4)2(OH)5 : a Raman spectroscopic study of a hydroxy-arsenate mineral

The mineral dussertite, a hydroxy-arsenate mineral of formula BaFe3+3(AsO4)2(OH)5, has been studied by Raman complimented with infrared spectroscopy. The spectra of three minerals from different origins were investigated and proved quite similar, although some minor differences were observed. In the Raman spectra of Czech dussertite, four bands are observed in the 800 to 950 cm-1 region. The bands are assigned as follows: the band at 902 cm-1 is assigned to the (AsO4)3- ν3 antisymmetric stretching mode, at 870 cm-1 to the (AsO4)3- ν1 symmetric stretching mode, and both at 859 cm-1 and 825 cm-1 to the As-OM2+/3+ stretching modes/and or hydroxyls bending modes. Raman bands at 372 and 409 cm-1 are attributed to the ν2 (AsO4)3- bending mode and the two bands at 429 and 474 cm-1 are assigned to the ν4 (AsO4)3- bending mode. An intense band at 3446 cm-1 in the infrared spectrum and a complex set of bands centred upon 3453 cm-1 in the Raman spectrum are attributed to the stretching vibrations of the hydrogen bonded (OH)- units and/or water units in the mineral structure. The broad infrared band at 3223 cm-1 is assigned to the vibrations of hydrogen bonded water molecules. Raman spectroscopy identified Raman bands attributable to (AsO4)3- and (AsO3OH)2- units.

4-Carbamoylpiperidinium 5-nitrosalicylate

In the structure of the title compound, C6H13N2O+ C7H4NO5-, the isonipecotamide cations and the 5-nitrosalicylate anions form hydrogen-bonded chain substructures through head-to-tail piperidinium N---H...O(carboxyl) hydrogen bonds and through centrosymmetric cyclic head-to-head amide-amide hydrogen-bonding associations [graph set R2/2(8)]. These chains are cross linked by amide N---H...O~carboxyl~ and piperidinium N-H...O(nitro) associations to give a two-dimensional sheet structure.

catena-Poly[[[diaquacobalt(II)]-mu-(3,5-dinitro-2-oxidobenzoato)-kappa3O1,O2:O1'-[tetraaquacobalt(II)]-mu-(3,5-dinitro-2-oxidobenzoato)-kappa3-O1:O1',O2] dihydrate]

In the structure of polymeric title compound, {[Co2(C7H2N2O7)2(H2O)6] . 2H2O}n from the reaction of 3,5-dinitrosalicylic acid with cobalt(II) acetate, both slightly distorted octahedral Co(II) centres have crystallographic inversion symmetry. The coordination sphere about one Co centre comprises four O donors from two bidentate chelate O(phenolate), O(carboxyl) and bridging dianionic ligands and two water molecules [Co-O range, 2.0249(11)-2.1386(14)A] while that about the second Co centre has four water molecules and two bridging carboxyl O donor atoms [Co-O range, 2.0690(14)-2.1364(11)A]. The coordinated water molecules as well as the water molecules of solvation give water-water and water-carboxyl hydrogen-bonding interactions in the three-dimensional framework structure.

Hydrogen bonding in proton-transfer compounds of 5-sulfosalicylic acid with a series of aliphatic nitrogen Lewis bases

The crystal structures of the proton-transfer compounds of 5-sulfosalicylic acid (3-carboxy-4-hydroxybenzenesulfonic acid) with the aliphatic nitrogen Lewis bases, hydroxylamine, triethylamine, pyrrolidine, morpholine, N-methylmorpholine and piperazine, viz. hydroxyammonium 3-carboxy-4-hydroxybenzenesulfonate (1), triethylaminium 3-carboxy-4-hydroxybenzenesulfonate (2), pyrrolidinium 3-carboxy-4-hydroxybenzenesulfonate monohydrate (3), morpholinium 3-carboxy-4-hydroxybenzenesulfonate monohydrate (4), N-methylmorpholinium 3-carboxy-4-hydroxybenzenesulfonate monohydrate (5) and piperazine-1,4-diium bis(3-carboxy-4-hydroxybenzenesulfonate) hexahydrate (6) have been determined and their comparative structural features and hydrogen-bonding patterns described. Crystals of 4 are triclinic, space group P-1 while the remainder are monoclinic with space group either P21/c (1 - 3) or P21/n (5, 6). Unit cell dimensions and contents are: for 1, a = 5.0156(3), b = 10.5738(6), c = 18.4785(9) Å, β = 96.412(5)o, Z = 4; for 2, a = 8.4998(4), b = 12.3832(6), c = 15.4875(9) Å, β = 102.411(5)o, Z = 4; for 3, a = 6.8755(2), b = 15.5217(4), c = 12.8335(3) Å, β = 92.074(2)o, Z = 4; for 4, a = 6.8397(2), b = 12.9756(5), c = 15.8216(6) Å, α = 90.833(3), β = 95.949(3), γ = 92.505(3)o, Z = 4; for 5, a = 7.0529(3), b = 13.8487(7), c = 15.6448(6) Å, β = 90.190(6)o, Z = 4; for 6, a = 7.0561(2), b = 15.9311(4), c = 12.2102(3) Å, β = 100.858(3)o, Z = 2. The hydrogen bonding generates structures which are either two-dimensional (2 and 5) or three-dimensional (1, 3, 4 and 6). Compound 6 represents the third reported structure of a salt of 5-sulfosalicylic acid having a dicationic piperazine species.

Pseudo-merohedral twinning in the structure of the hydrated 1:1 proton-transfer compound of 5-sulfosalicylic acid with 4-aminopyridine

The structure of the pseudo-merohedrally twinned crystal of the 1:1 proton-transfer compound of 5-sulfosalicylic acid (3-carboxy-4-hydroxybenzenesulfonic acid) with 4-aminopyridine: 4-aminopyridinium 3-carboxy-4-hydroxybenzenesulfonate sesquihydrate has been determined at 180 K and the hydrogen-bonding pattern is described. Crystals of the compound are monoclinic with space group P21/c, with unit cell dimensions a = 35.2589(8), b = 7.1948(1), c = 24.5851(5) Å, β = 110.373(2)o, and Z = 16. The monoclinic asymmetric unit comprises four cation-anion pairs and six water molecules of solvation with only the pyridinium cations having pseudo-symmetry as a result of inter-cation aromatic ring π-π stacking effects. Extensive hydrogen bonding gives a three-dimensional framework structure.

Long term immunity to live attenuated Japanese encephalitis chimeric virus vaccine : randomized, double-blind, 5-year phase II study in healthy adults.

In a randomized, double-blind study, 202 healthy adults were randomized to receive a live, attenuated Japanese encephalitis chimeric virus vaccine (JE-CV) and placebo 28 days apart in a cross-over design. A subgroup of 98 volunteers received a JE-CV booster at month 6. Safety, immunogenicity, and persistence of antibodies to month 60 were evaluated. There were no unexpected adverse events (AEs) and the incidence of AEs between JE-CV and placebo were similar. There were three serious adverse events (SAE) and no deaths. A moderately severe case of acute viral illness commencing 39 days after placebo administration was the only SAE considered possibly related to immunization. 99% of vaccine recipients achieved a seroprotective antibody titer ≥ 10 to JE-CV 28 days following the single dose of JE-CV, and 97% were seroprotected at month 6. Kaplan Meier analysis showed that after a single dose of JE-CV, 87% of the participants who were seroprotected at month 6 were still protected at month 60. This rate was 96% among those who received a booster immunization at month 6. 95% of subjects developed a neutralizing titer ≥ 10 against at least three of the four strains of a panel of wild-type Japanese encephalitis virus (JEV) strains on day 28 after immunization. At month 60, that proportion was 65% for participants who received a single dose of JE-CV and 75% for the booster group. These results suggest that JE-CV is safe, well tolerated and that a single dose provides long-lasting immunity to wild-type strains

meso-Porphyrinylphosphine Oxides: Mono- and Bidentate Ligands for Supramolecular Chemistry and the Crystal Structures of Monomeric [10,20-Diphenylporphyrinatonickel(II)-5,15-diyl]-bis-[P(O)Ph2] and Polymeric Self-Coordinated ([10,20-Diphenylporphyrinatozinc(II)-5,15-diyl]-bis-[P(O)Ph2])

A series of porphyrins substituted in one or two meso-positions by diphenylphosphine oxide groups has been prepared by the palladium catalysed reaction of diphenylphosphine or its oxide with the corresponding bromoporphyrins. Compounds {MDPP-[P(O)Ph2]n} (M = H2, Ni, Zn; H2DPP = 5,15-diphenylporphyrin; n = 1, 2) were isolated in yields of 60-95%. The reaction is believed to proceed via the conventional oxidative addition, phosphination and reductive elimination steps, as the stoichiometric reaction of η1-palladio(II) porphyrin [PdBr(H2DPP)(dppe)] (H2DPP = 5,15-diphenylporphyrin; dppe = 1,2-bis(diphenylphosphino)ethane) with diphenylphosphine oxide also results in the desired mono-porphyrinylphosphine oxide [H2DPP-P(O)Ph2]. Attempts to isolate the tertiary phosphines failed due to their extreme air-sensitivity. Variable temperature 1H NMR studies of [H2DPP-P(O)Ph2] revealed an intrinsic lack of symmetry, while fluorescence spectroscopy showed that the phosphine oxide group does not behave as a "heavy atom" quencher. The electron withdrawing effect of the phosphine oxide group was confirmed by voltammetry. The ligands were characterised by multinuclear NMR and UV-visible spectroscopy as well as mass spectrometry. Single crystal X-ray crystallography showed that the bis(phosphine oxide) nickel(II) complex {[NiDPP-[P(O)Ph2]2} is monomeric in the solid state, with a ruffled porphyrin core and the two P=O fragments on the same side of the average plane of the molecule. On the other hand, the corresponding zinc(II) complex formed infinite chains through coordination of one Ph2PO substituent to the neighbouring zinc porphyrin through an almost linear P=O---Zn unit, leaving the other Ph2PO group facing into a parallel channel filled with disordered water molecules. These new phosphine oxides are attractive ligands for supramolecular porphyrin chemistry.

New palladium catalysed reactions of bromoporphyrins: synthesis and crystal structures of nickel(II) complexes of primary 5-aminoporphyrin, 5,5’-bis(porphyrinyl) secondary amine, and 5-hydroxyporphyrin

Primary aminoporphyrin, secondary bis(porphyrinyl)amine and hydroxyporphyrin complexes have been isolated and characterised both spectroscopically and crystallographically from the reaction of 5-bromo-10,15,20-triphenylporphyrinato-nickel(II) with hydrazine under palladium catalysis.