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1.
J Nanobiotechnology ; 18(1): 67, 2020 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-32345323

RESUMO

BACKGROUND: Exenatide is an insulinotropic peptide drug for type 2 diabetes treatment with low risk of hypoglycemia, and is administrated by subcutaneous injection. Oral administration is the most preferred route for lifelong treatment of diabetes, but oral delivery of peptide drug remains a significant challenge due to the absorption obstacles in gastrointestinal tract. We aimed to produce exenatide-loaded nanoparticles containing absorption enhancer, protectant and stabilizer using FDA approved inactive ingredients and easy to scale-up method, and to evaluate their long-term oral therapeutic effect in type 2 diabetes db/db mice. RESULTS: Two types of nanoparticles, named COM NPs and DIS NPs, were fabricated using anti-solvent precipitation method. In COM NPs, the exenatide was complexed with cholic acid and phosphatidylcholine to increase the exenatide loading efficiency. In both nanoparticles, zein acted as the cement and the other ingredients were embedded in zein nanoparticles by hydrophobic interaction. Casein acted as the stabilizer. The nanoparticles had excellent lyophilization, storage and re-dispersion stability. Hypromellose phthalate protected the loaded exenatide from degradation in simulated gastric fluid. Cholic acid promoted the intestinal absorption of the loaded exenatide via bile acid transporters. The exenatide loading efficiencies of COM NPs and DIS NPs were 79.7% and 53.6%, respectively. The exenatide oral pharmacological availability of COM NPs was 18.6% and DIS NPs was 13.1%. COM NPs controlled the blood glucose level of the db/db mice well and the HbA1c concentration significantly decreased to 6.8% during and after 7 weeks of once daily oral administration consecutively. Both DIS NPs and COM NPs oral groups substantially increased the insulin secretion by more than 60% and promoted the ß-cell proliferation by more than 120% after the 7-week administration. CONCLUSIONS: Both COM NPs and DIS NPs are promising systems for oral delivery of exenatide, and COM NPs are better in blood glucose level control than DIS NPs. Using prolamin to produce multifunctional nanoparticles for oral delivery of peptide drug by hydrophobic interaction is a simple and effective strategy.

2.
Biomaterials ; 238: 119844, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32062148

RESUMO

Mitochondrial dysfunction is an early event of Alzheimer's disease (AD), contributes the onset and progression of AD, and may represent an effective therapeutic target for AD intervention. Since mitochondria in central neurons are more susceptible to oxidative damage than non-neuronal cells, the specific delivery of the antioxidants to the mitochondria of impaired central neurons is crucial for achieving the therapeutic effect on AD. Here, we prepare the neuronal mitochondria-targeted micelles (CT-NM) through co-decoration with neural cell adhesion molecule (NCAM) mimetic peptide C3 for brain neuron specific binding and the triphenylphosphonium (TPP) for mitochondrial targeting. CT-NM significantly increase the encapsulated resveratrol's concentration in the neuronal mitochondria compared to the micelles modified with C3 only or the resveratrol solution. The resveratrol-loaded CT-NM alleviate the oxidative stress in the neuronal cells, resulting in stabilization of the dynamic balance of mitochondrial fission and fusion. The targeted micelles restore the cognitive performance in APP/PS1 transgenic mice to the level of wild-type mice characterized by up-regulation of sirtuin 1 expression, reduction of amyloid deposition and tau hyperphosphorylation, protection of synapses and inhibition of microglia proliferation. The results demonstrate the delay of the progression of AD through reversing neuronal mitochondrial dysfunction by the targeted delivery of antioxidants.

3.
J Control Release ; 320: 347-362, 2020 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-31978446

RESUMO

The presence of blood-brain barrier (BBB) and specificity of neuron targeting remain two challenges in the effective delivery of nanotherapeutics for the treatment of Alzheimers disease (AD). Traditional strategy of nanocarriers for AD treatment involves co-decoration of both BBB-penetrating ligand and neuron-targeting ligand on the surface of the nanoparticles for "dual-stage" targeted delivery. Instead, we design and optimize a fusion peptide TPL comprising a BBB-penetrating peptide TGN and a neuron binding peptide Tet1 through a four-glycine linker. Compared to the mono-ligand Tet1 or CGN which is the retro-inverso isomer of TGN with higher brain targeting than TGN, the dual-ligand fusion peptide TPL has preferable blood stability and enhanced structural flexibility, resulting in higher binding affinity to either GT1b ganglioside receptor or brain capillary endothelial bEnd.3 cells. The TPL-modified nanoparticles (TPL-NP) increased the BBB-penetration and neuron-targeting efficacy than the nanoparticles co-decorated with the two mono-ligands. Encapsulation of a neuroprotective peptide NAP, TPL-NP significantly enhance reactive oxygen species scavenging ability and effectively protect microtubule from Aß25-35-induced neurotoxicity. Meanwhile, TPL-NP inhibit okadaic acid-induced tau aggregation and neuronal apoptosis. Administration of TPL-NP in AD mice also significantly improves the cognitive performance, down-regulates the tau phosphorylation level, promotes axonal transport and attenuates microgliosis. Taken together, this work demonstrates that the rationally designed dual-ligand fusion peptides can greatly improve the delivery of drugs to the AD lesions, thereby markedly enhancing the efficacy of AD treatment.

4.
Brain Res ; 1726: 146537, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31672473

RESUMO

Higher visual centers could modulate visually-guided ocular growth, in addition to local mechanisms intrinsic to the eye. There is evidence that such central modulations could be species (even subspecies)-dependent. While the mouse has recently become an important experimental animal in myopia studies, it remains unclear whether and how visual centers modulate refractive development in mice, an issue that was examined in the present study. We found that optic nerve crush (ONC), performed at P18, could modify normal refractive development in the C57BL/6 mouse raised in normal visual environment. Unexpectedly, sham surgery caused a steeper cornea, leading to a modest myopic refractive shift, but did not induce significant changes in ocular axis length. ONC caused corneal flattening and re-calibrated the refractive set-point in a bidirectional manner, causing significant myopic (<-3 D, 54.5%) or hyperopic (>+3 D, 18.2%) shifts in refractive error in most (totally 72.7%) animals, both due to changes in ocular axial length. ONC did not change the density of dopaminergic amacrine cells, but increased retinal levels of dopamine and DOPAC. We conclude that higher visual centers are likely to play a role in fine-tuning of ocular growth, thus modifying refractive development in the C57BL/6 mouse. The changes in refractive error induced by ONC are accounted for by alternations in multiple ocular dimensions, including corneal curvature and axial length.

5.
Acta Pharm Sin B ; 9(3): 590-603, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31193846

RESUMO

Gene therapy represents a promising treatment for the Alzheimer׳s disease (AD). However, gene delivery specific to brain lesions through systemic administration remains big challenge. In our previous work, we have developed an siRNA nanocomplex able to be specifically delivered to the amyloid plaques through surface modification with both CGN peptide for the blood-brain barrier (BBB) penetration and QSH peptide for ß-amyloid binding. But, whether the as-designed nanocomplex could indeed improve the gene accumulation in the impaired neuron cells and ameliorate AD-associated symptoms remains further study. Herein, we prepared the nanocomplexes with an siRNA against ß-site amyloid precursor protein-cleaving enzyme 1 (BACE1), the rate-limiting enzyme of Aß production, as the therapeutic siRNA of AD. The nanocomplexes exhibited high distribution in the Aß deposits-enriched hippocampus, especially in the neurons near the amyloid plaques after intravenous administration. In APP/PS1 transgenic mice, the nanocomplexes down-regulated BACE1 in both mRNA and protein levels, as well as Aß and amyloid plaques to the level of wild-type mice. Moreover, the nanocomplexes significantly increased the level of synaptophysin and rescued memory loss of the AD transgenic mice without hematological or histological toxicity. Taken together, this work presented direct evidences that the design of precise gene delivery to the AD lesions markedly improves the therapeutic outcome.

6.
World Neurosurg ; 117: e362-e370, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29909214

RESUMO

OBJECTIVE: To investigate the importance and types of peritumoral draining veins in parasagittal and falcine meningiomas and administer corresponding protective strategies during surgery according to these different types to improve tumor resection rate and maximize the protection of neurologic functions. METHODS: The clinical information of 156 patients with parasagittal and falcine meningiomas who were admitted at the Neurosurgery Department of our hospital was collected and retrospectively analyzed. All patients underwent pathologic classification, magnetic resonance imaging scanning and enhancement, and magnetic resonance venography examinations. RESULTS: Among these patients, 113 (72.4%) had Simpson grade I and II resection, whereas 43 patients (27.6%) had Simpson grade III and IV resection and underwent postoperative adjuvant gamma knife surgery. Karnofsky Performance Status evaluation was carried out at 1 week after surgery. In total, 69 patients (44.3%) improved, 66 patients (42.3%) had no changes, and 21 patients (13.4%) had worsened conditions (7 patients had hemiplegia, 5 patients had aphasia, 4 patients had decreased vision, and 5 patients had ataxia). There were no deaths. According to the 2016 World Health Organization pathologic grading, 131 patients (84%) were grade I, 22 patients (14%) were grade II, and 3 patients were grade III (2%). Furthermore, 105 patients were followed up for 1-4 years. There were 11 cases of recurrence. CONCLUSIONS: The classification and evaluation of peritumoral draining veins through preoperative-combined magnetic resonance venography can be used as a guide in determining the corresponding protective strategy during surgery. This can significantly improve the tumor resection rate and decrease the postoperative disability rate.


Assuntos
Neoplasias Meníngeas/irrigação sanguínea , Meningioma/irrigação sanguínea , Veias/cirurgia , Adulto , Idoso , Feminino , Humanos , Angiografia por Ressonância Magnética , Masculino , Neoplasias Meníngeas/cirurgia , Meningioma/cirurgia , Pessoa de Meia-Idade , Tratamentos com Preservação do Órgão/métodos , Flebografia/métodos , Resultado do Tratamento
7.
J Control Release ; 279: 220-233, 2018 06 10.
Artigo em Inglês | MEDLINE | ID: mdl-29679667

RESUMO

ß-site amyloid precursor protein cleaving enzyme 1 (BACE1) is a key enzyme to cleave the amyloid precursor protein to develop Alzheimer's disease (AD). Reducing BACE1 expression in central neuron through RNA interference technology shows great promise to overcome AD. However, to obtain an efficient and neurons-specific delivery of siRNA against BACE1 through systemic administration remains challenging. Here, we design and prepare siRNA nano-carriers based on PEGylated poly(2-(N,N-dimethylamino) ethyl methacrylate) (PEG-PDMAEMA) modified with both the CGN peptide for blood-brain barrier (BBB) penetration and the Tet1 peptide for neuron-specific binding. The nanocomplexes CT/siRNA, composed of CGN-PEG-PDMAEMA and Tet1-PEG-PDMAEMA at a weight ratio of 1:1, display a good stability in the blood and do not lead to hemolysis at N/P = 10. The internalization of nanocomplexes in neuron cells relies on clathrin-mediated endocytosis and micropinocytosis, while caveolae-mediated endocytosis plays a major role in entrance of CT/siRNA into cerebral capillary endothelial cell bEnd.3. The nanocomplexes successfully escape from lysosomes and enter in the cytoplasm of the neuron cells, inducing effective gene silence (about 50% decrease in BACE1 mRNA levels) and reversing Aß25-35 oligomer-induced synaptic injury. After caudal vein injection in mice, CT/siRNA display higher brain accumulation than unmodified nanocomplexes (brain drug targeting index = 2.62), and colocalize with neurons or locate nearby. In APP/PS1 transgenic mice, the nanocomplexes significantly decrease BACE1 mRNA and the amyloid plaques, suppress phosphorylated tau protein levels, as well as promote hippocampal neurogenesis. Noticeably, administration of the nanocomplexes restores the cognitive performance of the AD transgenic mice to the level of wild-type control without significant adverse effects on myelination. Our results demonstrate the CT/siRNA nanocomplexes capable of specifically directing BACE1 siRNA to brain neurons with great potential for AD therapy.


Assuntos
Doença de Alzheimer/terapia , Secretases da Proteína Precursora do Amiloide/genética , Ácido Aspártico Endopeptidases/genética , Encéfalo/metabolismo , Nanopartículas , RNA Interferente Pequeno/administração & dosagem , Doença de Alzheimer/genética , Doença de Alzheimer/fisiopatologia , Precursor de Proteína beta-Amiloide/metabolismo , Animais , Barreira Hematoencefálica/metabolismo , Transtornos Cognitivos/genética , Transtornos Cognitivos/terapia , Proteínas de Ligação a DNA/metabolismo , Modelos Animais de Doenças , Endocitose/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos ICR , Camundongos Transgênicos , Neurônios/metabolismo , Placa Amiloide/metabolismo , Polímeros/química , Proteínas Proto-Oncogênicas/metabolismo , RNA Interferente Pequeno/farmacocinética , RNA Interferente Pequeno/toxicidade
8.
Invest Ophthalmol Vis Sci ; 57(13): 5393-5404, 2016 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-27737460

RESUMO

Purpose: Although retinal dopamine (DA) has been long implicated in myopia development, current studies demonstrate that retinal DA levels are unaltered in C57BL/6 mice with form-deprivation myopia. This work was undertaken to explore whether and how refractive development is perturbed in this mouse strain when retinal DA levels are reduced by 6-hydroxydopamine (6-OHDA) administration. Methods: On two successive days, 6-OHDA was injected into the vitreous of P18 mice. Retinal DA levels were measured by HPLC and TH levels analyzed by quantitative Western blotting. To choose appropriate 6-OHDA doses that significantly reduce retinal DA levels, but cause minimal disturbance of overall retinal physiology, ERG analysis was performed. Refractive errors were measured using a photorefractor, and ocular biometry performed with optical coherence tomography and photokeratometry. Results: Administration of 6-OHDA of 6.25 µg and 12.5 µg significantly reduced retinal levels of DA and TH, but without affecting ERG a- and b-wave amplitudes. With normal visual experience, 6-OHDA induced myopic refractive shifts in a dose-dependent fashion. Form deprivation induced further myopic shifts in 6-OHDA-injected eyes, but did not cause further decline in retinal DA. Furthermore, 6-OHDA administration resulted in a shorter axial length and a steeper cornea, whereas form deprivation led to a longer axial length, without changing the corneal radius of curvature. Conclusions: Reducing retinal DA levels led to myopic refractive shifts in C57BL/6 mice, which mainly resulted from a steeper cornea. In addition to the DA-independent mechanism for form-deprivation myopia, there is a DA-dependent mechanism in parallel that underlies myopic refractive shifts under normal laboratory conditions in this mouse strain.


Assuntos
Dopamina/metabolismo , Miopia/metabolismo , Oxidopamina/administração & dosagem , Refração Ocular , Retina/metabolismo , Tomografia de Coerência Óptica/métodos , Adrenérgicos/administração & dosagem , Animais , Western Blotting , Cromatografia Líquida de Alta Pressão , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Eletrorretinografia , Seguimentos , Injeções Intravítreas , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Miopia/diagnóstico , Retina/patologia , Retina/fisiopatologia
9.
Sheng Li Xue Bao ; 68(2): 135-40, 2016 Apr 25.
Artigo em Chinês | MEDLINE | ID: mdl-27108899

RESUMO

Due to the advantages in genetic manipulation, mice have become one of the most commonly used mammalian models for the study of mechanisms underlying myopia development. However, the vast majority of laboratory mouse strains are incapable of synthesizing melatonin, a neurohormone that may play an important role in myopia generation in humans. The present study investigated refractive development profiles in the CBA/CaJ mouse, a strain proficient in melatonin, and determined whether and how its refractive development could be affected by form-deprivation. Eccentric infrared photoretinoscopy revealed that this animal could be stably refracted, and the refractive error underwent developmental changes, which increased with age in the hyperopic direction and eventually got stable approximately 9 weeks after birth. The absolute values of refractive error in CBA/CaJ mice were larger than those of age-matched C57BL/6 mice, whereas the time points when refractive error reached steady state were similar between the two strains. Five weeks of form-deprivation applied to 3-week-old CBA/CaJ mice by translucent occluder wear caused a significant myopic shift in refractive error, indicating that this strain could be adequately used as a myopia model.


Assuntos
Refração Ocular , Privação Sensorial , Animais , Modelos Animais de Doenças , Olho , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos CBA , Miopia
10.
Invest Ophthalmol Vis Sci ; 56(2): 967-77, 2015 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-25604682

RESUMO

PURPOSE: Retinal dopamine has been long implicated in the signaling pathway regulating eye growth, as evidenced by its reduced levels in myopic eyes in various species. We examined whether and how retinal dopamine levels were changed in a C57BL/6 mouse model of experimental myopia. METHODS: Form-deprivation myopia (FDM) was induced in C57BL/6 mice by wearing monocular occluder for 4 weeks. Refractive errors were measured using an infrared photorefractor. Retinal dopamine/DOPAC and vitreal DOPAC levels were assessed by high-performance liquid chromatography (HPLC). Extracellular dopamine concentrations were examined by Western blot analysis of dopamine transporter (DAT) expression levels. The intactness of retinal dopaminergic system was evaluated by counting tyrosine hydroxylase (TH) immunoreactive cells, measuring the areas occupied by processes of these cells, and quantifying retinal TH expression at both protein and transcription levels. RESULTS: Form-deprivation myopia was successfully induced in C57BL/6 mice with the refractive status of deprived eyes being significantly different from fellow eyes. Unlike most of the previous results obtained in other myopic animal models, however, no significant changes in retinal dopamine, DOPAC, DAT, and vitreal DOPAC levels were detected in deprived eyes, either in the daytime or at night. Furthermore, neither the number of dopaminergic amacrine cells, the area size occupied by the processes of these cells, nor retinal TH expression, were altered in deprived eyes. CONCLUSIONS: The retinal dopamine system remains intact in C57BL/6 mice with FDM, and retinal dopamine levels are not associated with the development of FDM in this mouse strain.


Assuntos
Dopamina/metabolismo , Miopia/metabolismo , Refração Ocular/fisiologia , Retina/metabolismo , Animais , Biomarcadores/metabolismo , Modelos Animais de Doenças , Progressão da Doença , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Miopia/etiologia , Miopia/fisiopatologia , Privação Sensorial
11.
Chem Sci ; 6(8): 4587-4593, 2015 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-29568416

RESUMO

A dysprosium based single-ion magnet is synthesized and characterized by the angular dependence of the single-crystal magnetic susceptibility. Ab initio and effective electrostatic analyses are performed using the molecular structures determined from single crystal X-ray diffraction at 20 K, 100 K and 300 K. Contrary to the common assumption, the results reveal that the structural thermal effects that may affect the energy level scheme and magnetic anisotropy below 100 K are negligible.

12.
Dalton Trans ; 43(31): 11897-907, 2014 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-24967573

RESUMO

A new family of enantiopure star-shaped Fe(III)4 single-molecule magnets (SMMs) with the general formula [Fe4(L(K))6] (H2L = (R or S)-2-((2-hydroxy-1-phenylethylimino methyl)phenol); K = H (), Cl (), Br (), I (), and t-Bu ()), were structurally and magnetically characterized. Complex was reported in our previous paper (Chem. Commun., 2011, 47, 8049-8051). Detailed magnetic measurements and a systematic magneto-structural correlation study revealed that the SMM properties of this series of compounds can be finely tuned by the remote substituent of the ligands. Although the change in the coordination environment of the central Fe(3+) ions is very small, the properties of SMM behavior are changed considerably. All five complexes display frequency dependence of the ac susceptibility. However, the χ peaks of complexes and cannot be observed down to 0.5 K. The fitted anisotropy energy barriers (Ueff) of complexes , , and were 5.9, 7.1, and 11.0 K, respectively. Moreover, the hysteresis loops of these three complexes can be also observed around 0.5 K. Magneto-structural correlation analyses revealed that the coordination symmetry of the central Fe(3+) ion and the intermolecular interaction are two key factors affecting the SMM properties. Deviation to a trigonal prism coordination environment and the existence of intermolecular interactions between neighboring clusters may both reduce the anisotropy energy barriers.

13.
Chemistry ; 19(1): 294-303, 2013 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-23225116

RESUMO

By using the node-and-spacer approach in suitable solvents, four new heterotrimetallic 1D chain-like compounds (that is, containing 3d-3d'-4f metal ions), {[Ni(L)Ln(NO(3))(2)(H(2)O)Fe(Tp*)(CN)(3)]⋅2 CH(3)CN⋅CH(3)OH}(n) (H(2)L = N,N'-bis(3-methoxysalicylidene)-1,3-diaminopropane, Tp* = hydridotris(3,5-dimethylpyrazol-1-yl)borate; Ln = Gd (1), Dy (2), Tb (3), Nd (4)), have been synthesized and structurally characterized. All of these compounds are made up of a neutral cyanide- and phenolate-bridged heterotrimetallic chain, with a {-Fe-C≡N-Ni(-O-Ln)-N≡C-}(n) repeat unit. Within these chains, each [(Tp*)Fe(CN)(3)](-) entity binds to the Ni(II) ion of the [Ni(L)Ln(NO(3))(2)(H(2)O)](+) motif through two of its three cyanide groups in a cis mode, whereas each [Ni(L)Ln(NO(3))(2)(H(2)O)](+) unit is linked to two [(Tp*)Fe(CN)(3)](-) ions through the Ni(II) ion in a trans mode. In the [Ni(L)Ln(NO(3))(2)(H(2)O)](+) unit, the Ni(II) and Ln(III) ions are bridged to one other through two phenolic oxygen atoms of the ligand (L). Compounds 1-4 are rare examples of 1D cyanide- and phenolate-bridged 3d-3d'-4f helical chain compounds. As expected, strong ferromagnetic interactions are observed between neighboring Fe(III) and Ni(II) ions through a cyanide bridge and between neighboring Ni(II) and Ln(III) (except for Nd(III) ) ions through two phenolate bridges. Further magnetic studies show that all of these compounds exhibit single-chain magnetic behavior. Compound 2 exhibits the highest effective energy barrier (58.2 K) for the reversal of magnetization in 3d/4d/5d-4f heterotrimetallic single-chain magnets.

14.
Chemistry ; 18(25): 7869-77, 2012 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-22544442

RESUMO

Three coordination polymers, [Cd(2)(pvba)(2)(tbdc)(dmf)(2)] (1), [Co(2)(pvba)(2)(tbdc)(dmf)(2)(H(2)O)(2)] (2), and [Ni(2)(pvba)(2)(tbdc)(dmf)(2)(H(2)O)(2)] (3) (H(2)tbdc = 2,3,5,6-tetrabromobenzenedicarboxylic acid, Hpvba = trans-2-(4'-pyridyl)vinylbenzoic acid), were synthesized by solvothermal methods. The solid-state structures of compounds 1 and 2 were determined by X-ray crystallography. In compounds 1 and 2, the bimetallic cores acted as secondary building units that connected the tbdc ligands in one direction and a pair of pvba ligands, which were aligned in a head-to-tail parallel manner, in the orthogonal direction to form sheet structures. The C=C bonds in these pvba ligand pairs in all three compounds were well-aligned to undergo quantitative [2+2] cycloaddition reactions in the solid state under UV irradiation, thereby yielding their cyclobutane derivatives. This photochemical reaction appeared to facilitate structural transformations from one 2D structure into another in the solid state. The photoreactive Co(II)- and Ni(II) coordination polymers exhibited a reversible dehydration-rehydration reaction that was accompanied by color changes from pink to purple and green to yellow, respectively, owing to a change in coordination number from six to five. Magnetic studies showed that compound 2 was an antiferromagnet, which displayed a field-dependent transition with a critical field (H(c)) of 40 kOe at 2 K; the antiferromagnetic interaction between the Co(2) units was strengthened and weakened by dehydration and UV irradiation, respectively. The cyclobutane ligand in the photodimerized products was cleaved on heating to yield a mixture of trans- and cis-isomers of pvba, as monitored by (1)H NMR spectroscopy. The Cd(II) coordination polymer underwent quantitative cleavage of the cyclobutane ring whilst the other two underwent partial cleavage.

15.
Dalton Trans ; 41(19): 5794-8, 2012 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-22327897

RESUMO

Reaction of [Ru(VI)(N)(sap)Cl] with excess NaN(3) affords a novel paramagnetic triazidoruthenium(III) complex [Ru(III)(sap)(N(3))(3)](2-), which is isolated as a PPh(4)(+) salt (1). Reaction of 1 with Ni(2+) and Co(2+) ions produce two isostructural hexanuclear [Ru(4)M(2)] compounds, [Ru(IV)(4)M(II)(2)(µ(3)-OMe)(2)(µ-OMe)(2)(µ-N)(2)(µ-N(3))(2)(µ-O(phenoxy))(2)(sap)(4) (MeOH)(4)] (M = Ni 2 or Co 3). The molecular structures of 1-3 have been determined by X-ray crystallography. 1 is a mononuclear ruthenium(III) compound where three azide ligands are bonded to ruthenium in a meridional fashion, while compounds 2 and 3 are isostructural hexanuclear compounds containing a defective face-sharing dicubane-like core with two missing vertexes. Variable-temperature dc magnetic susceptibility studies have been carried out for 2 and 3. These data indicate that there are four diamagnetic Ru(IV) ions in 2 and 3 and there is ferromagnetic interaction between the two Ni(2+) in 2 and Co(2+) in 3 via the methoxy bridges.

16.
Chem Commun (Camb) ; 47(34): 9624-6, 2011 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-21773605

RESUMO

Homoleptic tetrakis[2,3,9,10,16,17,23,24-octa(butyloxy)phthalocyaninato] dysprosium-cadmium quadruple-decker complex 1 was isolated in relatively good yield of 43% from a simple one-pot reaction. This compound represents the first sandwich-type tetrakis(phthalocyaninato) rare earth-cadmium quadruple-decker SMM that has been structurally characterized.

17.
Chem Commun (Camb) ; 47(30): 8694-6, 2011 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-21725550

RESUMO

Reaction of [Ru(II)(PPh(3))(3)Cl(2)] with HQ and KCN produces a new dicyanoruthenium(III) building block, [Ru(III)(Q)(2)(CN)(2)](-). It reacts with hydrated CoCl(2) in MeOH or DMF to produce a trinuclear compound 2 or a 1-D zigzag chain 3.

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