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Rong Cao

Publications and source records attributed to Rong Cao.

32 records · Page 2Linked to original sources
PubMed2003

A three-dimensional manganeseII complex exhibiting ferrimagnetic and metamagnetic behaviors.

A three-dimensional complex, [Mn(3)(4-aba)(6)](n) (1) (4-Haba = 4-aminobenzoic acid), consisting of manganese(II) chains and 4-aba bridging ligands, has been synthesized and characterized. Magnetic studies show that the compound behaves as a three-dimensional metamagnet built of homometallic ferrimagnetic chains. The required noncompensation in spin moments is achieved by alternating interactions in an AF-AF-F sequence (AF = antiferromagnetic; F = ferromagnetic) by considering intrachain magnetic interactions.

Journal Article↗
PubMed2003

Synthesis and characterization of thermoreversible biopolymer microgels based on hydrogen bonded nucleobase pairing.

We describe the synthesis and characterization of a thermoreversibly cross-linked biopolymer microgel based on protein, DNA, and peptide nucleic acid (PNA) components. The DNA assembles into a trifunctional three-way junction (TWJ) with single-stranded overhangs. PNA oligomers complementary to these overhangs and bearing terminal biotin groups hybridize to the DNA TWJ and simultaneously bind to the tetrafunctional protein avidin, leading to a cross-linked system. Dynamic light scattering experiments reveal that micron-sized particles are formed. Static light scattering was used to characterize the internal structure of these microgels, which were found to have a fractal dimension of 1.85, indicative of a loose network structure. Heating disrupts the weakest component in the system, namely the PNA-DNA hybrid, resulting in dissolution of the microgel, while cooling restores the hydrogen bonding leading to reassembly of the microgel. Variation of the nucleotide sequence permits tuning of the gelation temperature with fine control.

Avidin↗
PubMed2002

Syntheses and characterizations of copper(II) polymeric complexes constructed from 1,2,4,5-benzenetetracarboxylic acid.

Four polymeric complexes with rectangular grids or channels, [Cu2(btec)(H2O)4*2H2O]n (2), [Cu2(btec)4/4[Cu(Hbtec)2/2(4,4'-Hbpy)(H2O)2]2*4H2O]n (3), [Cu2(btec)(hmt)(H2O)4*8H2O]n (4), and [Cu3(btec)(OH)2]n (5), were designed and constructed from Cu(II) ion and 1,2,4,5-benzenetetracarboxylic acid along with auxiliary ligands (where H4btec = 1,2,4,5-benzenetetracarboxylic acid, 4,4'-Hbpy = monoprotonated 4,4'-bipyridine, and hmt = hexamethylenetetramine). Complexes 2, 3, and 4 have rectangular pores with the size of 6.5 A x 4.5 A, 6 A x 7 A, and 10.1 A x 11.8 A, respectively, while 5 has a channel of 7.4 A x 9.6 A. The complexes show interesting magnetic properties due to the different coordination modes of the carboxylate groups and the presence of auxiliary ligands. On lowering the temperature, the magnetic interactions in 2 are changed from antiferromagnetic to ferromagnetic. For 3, the antiferromagnetic interactions weaken sharply at low temperature. Complex 4 shows ferromagnetic interactions while 5 is antiferromagnetic.

Journal Article↗
PubMed2002

Synthesis and reactions of group 6 metal half-sandwich complexes of 2,2-dicyanoethylene-1,1-dichalcogenolates [(Cp*)M[E(2)C=C(CN)(2)](2)]-(M = Mo, W; E = S, Se).

A series of group 6 transition metal half-sandwich complexes with 1,1-dichalcogenide ligands have been prepared by the reactions of Cp*MCl(4)(Cp* = eta(5)-C(5)Me(5); M = Mo, W) with the potassium salt of 2,2-dicyanoethylene-1,1-dithiolate, (KS)(2)C=C(CN)(2) (K(2)-i-mnt), or the analogous seleno compound, (KSe)(2)C=C(CN)(2) (K(2)-i-mns). The reaction of Cp*MCl(4) with (KS)(2)C=C(CN)(2) in a 1:3 molar ratio in CH(3)CN gave rise to K[Cp*M(S(2)C=C(CN)(2))(2)] (M = Mo, 1a, 74%; M = W, 2a, 46%). Under the same conditions, the reaction of Cp*MoCl(4) with 3 equiv of (KSe)(2)C=C(CN)(2) afforded K[Cp*Mo(Se(2)C=C(CN)(2))(2)] (3a) and K[Cp*Mo(Se(2)C=C(CN)(2))(Se(Se(2))C=C(CN)(2))] (4) in respective yields of 45% and 25%. Cation exchange reactions of 1a, 2a, and 3a with Et(4)NBr resulted in isolation of (Et(4)N)[Cp*Mo(S(2)C=C(CN)(2))(2)] (1b), (Et(4)N)[Cp*W(S(2)C=C(CN)(2))(2)] (2b), and (Et(4)N)[Cp*Mo(Se(2)C=C(CN)(2))(2)] (3b), respectively. Complex 4 crystallized with one THF and one CH(3)CN molecule as a three-dimensional network structure. Inspection of the reaction of Cp*WCl(4) with (KSe)(2)C=C(CN)(2) by ESI-MS revealed the existence of three species in CH(3)CN, [Cp*W(Se(2)C=C(CN)(2))(2)]-, [Cp*W(Se(2)C=C(CN)(2))(Se(Se(2))C=C(CN)(2))]-, and [Cp*W(Se(Se(2))C=C(CN)(2))(2)]-, of which [Cp*W(Se(2)C=C(CN)(2))(Se(Se(2))C=C(CN)(2))]-(5) was isolated as the main product. Treatment of 2a with 1/4 equiv of S(8) in refluxing THF resulted in sulfur insertion and gave rise to K[Cp*W(S(2)C=C(CN)(2))(S(S(2))C=C(CN)(2))](6), which crystallized with two THF molecules forming a three-dimensional network structure. 6 can also be prepared by refluxing 2a with 1/4 equiv of S(8) in THF. 3a readily added one Se atom upon treatment with 1 mol of Se powder in THF to give 4 in high yield, while the treatment of 3a or 4 with 2 equiv of Na(2)Se in THF led to formation of a dinuclear complex [(Cp*Mo)(2)(mu-Se)(mu-Se(Se(3))C=C(CN)(2))] (7). The structure of 7 consists of two Cp*Mo units bridged by a Se(2-) and a [Se(Se(3))C=C(CN)(2)](2-) ligand in which the triselenido group is arranged in a nearly linear way (163 degrees). The reaction of 2a with 2 equiv of CuBr in CH(3)CN yielded a trinuclear complex [Cp*WCu(2)(mu-Br)(mu(3)-S(2)C=C(CN)(2))(2)] (8), which crystallized with one CH(3)CN and generated a one-dimensional chain polymer through bonding of Cu to the N of the cyano groups.

Journal Article↗
PubMed2002

Immunocytochemical localization of substance P receptor in hypothalamic oxytocin-containing neurons of C57 mice.

With the use of double immunofluorescence, we have examined the distribution of oxytocin-containing neurons that express substance P receptor (SPR) in the hypothalamus of C57 mice. The distribution of oxytocin-like immunoreactive neurons overlapped with that of SPR-like immunoreactive neurons in the paraventricular nucleus and supraoptic nucleus of the hypothalamus. Neurons showing both oxytocin- and SPR-like immunoreactivities were predominantly found in both nuclei. A few neurons that were double-labeled with oxytocin- and SPR-like immunoreactivities were also scattered in the hypothalamic periventricular and preoptic regions. Semi-quantitative analysis indicated that about 94% of the oxytocin-like neurons displayed SPR-like immunoreactivity. These double-labeled cells constituted about 91% of the SPR-like neurons in the aforementioned regions. The present study provides morphological evidence for tachykinin-induced modulation of oxytocin-containing neurons as mediated by substance P receptor in the hypothalamus of mammals.

Animals↗
PubMed2002

Alkylation reactions of [WS(4)](2)(-) and [(eta(5)-C(5)Me(5))WS(3)](-) with 2,6-bis(bromomethyl)pyridine: the first isolation of bisalkylated tetrathiometalate WS(2)[2,6-(SCH(2))(2)(C(5)H(3)N)].

The trithio and tetrathio complexes of tungsten (PPh(4))[CpWS(3)] (Cp = eta(5)-C(5)Me(5)) and (PPh(4))(2)[WS(4)] undergo alkylation reactions with 2,6-bis(bromomethyl)pyridine to yield [(CpWS(2))(2)[2,6-(SCH(2))(2)(C(5)H(3)N)]].CH(3)CN (1.CH3CN) (73.1% yield) and WS(2)[2,6-(SCH(2))(2)(C(5)H(3)N)] (2) (76.0% yield), respectively. In the dinuclear complex 1, two CpWS(3) units are linked by a 2,6-dimethylenepyridine bridge, and the pyridine nitrogen is not coordinated at tungsten. Complex 2 is the first example of bisalkylated tetrathiometalates, the mononuclear structure of which is stabilized by coordination of the pyridine nitrogen.

Journal Article↗
PubMed2002

Syntheses and characterizations of three-dimensional channel-like polymeric lanthanide complexes constructed by 1,2,4,5-benzenetetracarboxylic acid.

The hydrothermal reaction of YbCl(3) small middle dot6H(2)O with 1,2,4,5-benzenetetracarboxylic dianhydride resulted in [[Yb((b)btec)(1/4)((d)btec)(3/6)(H(2)O)(2)](4).6H(2)O](n)() (1) (H(4)btec = 1,2,4,5-benzenetetracarboxylic acid), and the solvothermal reaction of Er(NO(3))(3) small middle dot6H(2)O or TbCl(3).6H(2)O with 1,2,4,5-benzenetetracarboxylic dianhydride in H(2)O/acetic acid gave rise to [[Er(2)((c)btec)(2/4)((e)btec)(2/4)((f)btec)(2/4)(H(2)O)(4)].4H(2)O](n)() (2) and [[Tb(H(2)btec)(2/4)((f)btec)(3/6)(H(2)O)].2H(2)O](n)() (3), respectively. Complex 1 crystallizes in monoclinic space group C2/m with a = 20.8119(5) A, b = 17.6174(1) A, c = 5.7252(2) A, beta = 92.324(1) degrees, and Z = 1. 1 possesses a three-dimensional framework consisting of eight-coordinate ytterbium centers and two kinds of channels along the c axis. Complex 2 crystallizes in triclinic space group P with a = 9.6739(5) A, b = 11.0039(5) A, c = 11.5523 A, alpha = 104.8330(10) degrees, beta = 91.0000(10) degrees, gamma = 114.2570(10) degrees, and Z = 2. 2 has a three-dimensional framework comprising both eight- and nine-coordinate erbium centers and channels along the a axis. Complex 3 crystallizes in monoclinic space group P2(1)/n with a = 10.7246(12) A, b = 7.1693(9) A, c = 17.158(2) A, beta = 97.109(2) degrees, and Z = 4. 3 shows a three-dimensional framework containing nine-coordinate terbium centers and channels along the b axis. Uncoordinated water molecules occupy the channels in the three complexes. TGA and XRPD were determined for the three complexes, and the results illustrate that the framework of 1 is retained upon removal of uncoordinated and coordinated water molecules.

Journal Article↗
PubMed2002

Enhancement of nestin protein-immunoreactivity induced by ionizing radiation in the forebrain ependymal regions of rats.

Expression of nestin was immunohistochemically examined in the forebrains of rats receiving ionizing radiation. Nestin-immunoreactive cells were predominately distributed in ependymal regions. Nestin-immunoreactivity in ependymal regions of irradiated rats increased significantly from 1 to 4 weeks after ionizing radiation compared with that of controls. Double immunofluorescence confirmed that about 94% of nestin-positive cells exhibited glial fibrillary acidic protein-immunoreactivity and a minor population of them showed Ki-67-immunoreactivity in these regions. The results have provided evidence for up-regulation of nestin expression induced by ionizing radiation in ependymal cells, suggesting that these reactive ependymal cells may be involved in remodeling and repairing processes of brain irradiation injury.

Animals↗
PubMed2000

Bis[bis(N,N-diethyl-1,1-diselenocarbamato)copper(II)], [Cu(Se(2)CNEt(2))(2)](2).

The title centrosymmetric Cu(II) binuclear complex, bis(micro-N,N-diethyl-1,1-diselenocarbamato-Se,Se':Se)bis[(N,N-diethyl-1,1-diselenocarbamato-Se,Se')copper(II)], [Cu(Se(2)CNEt(2))(2)](2) or [Cu(2)(C(5)H(10)NSe(2))(4)], is built from two symmetry-related [Cu{Se(2)CN(Et)(2)}(2)] units by pairs of Cu-Se bonds. The coordination geometry at the unique Cu atom is distorted square pyramidal, with Cu-Se distances in the range 2.4091 (11)-2.9095 (10) A.

Journal Article↗