Series of dinuclear and tetranuclear lanthanide clusters encapsulated by salen-type and ß-diketionate ligands: single-molecule magnet and fluorescence properties.

Three dinuclear [Ln2H2OL(1)2(acac)2]·solvent (1, Ln = Gd, solvent = 2CH2Cl2; 2, Ln = Tb, no solvent; 3, Ln = Er, solvent = (C2H5)2O), and two tetranuclear lanthanide clusters [Ln4(µ3-OH)2L(2)2(acac)6]·2(solvent) (4, Ln = Tb, solvent = CH3OH; 5, Ln = Dy, solvent = CH3CN) were characterized in terms of structure, fluorescence and magnetism. The dinuclear lanthanide complexes were constructed by a rigid salen-type ligand H2L(1) = N,N'-bis(salicylidene)-o-phenylenediamine and ß-diketonate (acac = acetylacetonate) ligands, while the tetranuclear clusters were formed from the flexible ligand H2L(2) = N,N'-bis(salicylidene)-1,2-ethanediamine. Crystal structure analysis indicates that the rigid ligand favors the double-decker sandwich structure (Ln2L(1)2), in which the two lanthanide ions have different coordination numbers and geometry, while the more flexible ligand (H2L(2)) leads to planar tetranuclear clusters. The relationship between their respective magnetic anisotropy and ligand-field geometries and their fluorescence properties was investigated. The Dy and Tb-containing clusters exhibit typical visible fluorescence properties, and single-molecule magnet behavior is seen in complex 5.

A salen-type trinuclear Zn2Gd complex.

In the trinuclear title complex, di-µ-acetato-1:2κ(2)O:O';2:3κ(2)O:O'-bis-{µ-6,6'-dimeth-oxy-2,2'-[cyclo-hexane-1,2-diylbis(methanylyl-idene)]diphenolato}-1:2κ(6)O(1),N,N',O(1'):O(6),O(6');2:3κ(6)O(6),O(6'):O(1),N,N',O(1')-2-gadolinium(III)-1,3-dizinc hexa-fluor-idophosphate methanol monosolvate monohydrate, [GdZn2(C22H24N2O4)2(CH3COO)2]PF6·CH3OH·H2O, the two Zn(II) ions are located in the inner N2O2 cavities of two 6,6'-dimeth-oxy-2,2'-[cyclo-hexane-1,2-diylbis(methanylyl-idene)]diphenolate (L) ligands. Both Zn(II) ions are five-coordinated by two O atoms and two N atoms from the L ligand and one O atom of an acetic acid mol-ecule, giving rise to a square-pyramidal geometry around the Zn(II) ions. The Gd(III) ion is nine-coordinated by four O atoms from the outer O2O2 sites of one ligand, and three O atoms from another ligand, in which there is one non-coordinating meth-oxy O atom. Two further O atom from different acetate ligands complete the nine-coordinate environment.

Dynamic changes in MRI of cerebral edema in rats after experimental cerebral infarction and intervention effect of mild hypotherma on them / 中华神经医学杂志

[Objective]To study the intervention effect of mild hypotherrnia on cerebral edema in rats after cerebral infarction.[Methods]Twelve male SD rats were randomized into control group (n--6) and mild hypotherma treatment group (n=6).The rat models of focal cerebral infarction were established with obstructing the middle cerebral artery of rats by suture emboli.Rats of the mild hypotherma treatment group were treated by mild hypotherm for 3 h after the models were established.MRI was performed at 6 h,and 1,3,5 and 7 d after the success of model making.Cerebral infarction volume,absorption rate of edema,and signal intensity ratios (SIRs) ofTIWl,T2WI,FLAIR and DWI sequencas in the infarction zones,and relative variance ratio of SIR (△SIR) were measured and calculated.[Results] In the mild hypotherma treatment group,the cerebral infarction volumes 3,5 and 7 d after the models were established were significantly decreased as compared with those in the control group (P＜0.05);the absorption rate of edema (the 7th d against the 3th d of infarction) in the the mild hypotherma treatment group was significantly higher than that in the control group (P＜0.05).Three,5 and 7 d after infarction,the SIRs of TIWI were all obviously higher than those in the control group,and the SIRs of T2WI and FLAIR were all significantly lower than those in the control group (P＜0.05).The SIR of DWI in the mild hypotherma treatment group was obviously lower than that in the control group 7 d after infarction (P＜0.05).The △SIRs of T2Wl,FLAIR and DWI in the mild hypotherma treatment group were significantly higher than those in the control group (P＜0.05).[Conclusion] Mild hypothermia has a significant inhibition effect on cerebral edema in rats after cerebral infarction.

Correlations between aquaporin 4 expression and MRI changes in rats with experimental hemorrhagic cerebral edema / 中华神经医学杂志

Objective To study the relation between aquaporin 4 (AQP4) expression in the perihematomal tissue and changes of MRI indicators after intracerebral hemorrhage of rats, and explore the relationship between AQP4 expression and formation of hemorrhagic brain edema. Methods Forty-five male SD rats were randomized into sham-operated group (n=15) and hemorrhage group (n=30). The rats of these groups were equally subdivided into the 1', 2nd, 3rd, 5th and 7th d measurement groups, respectively. The models of intracerebral hemorrhage were established by infusing collagenase into globus pallidus of the rats. MRI was performed 1, 2, 3, 5 and 7 d after the success of model making;edema volume around the hematoma and signal intensity ratio of T1WI, T2WI, and FLAIR sequences in the edema zone were measured and calculated. The rats were sacrificed at the corresponding time point after imaging. Immunohistochemistry staining was performed to observe the expression of AQP4 at each time point. Results The AQP4 expression level of perihematomal tissue in the hemorrhage group was obviously higher than that in the sham-operated group (P＜0.05). Liner positive correlation between the AQP4 expression level and the volume of cerebral edema around the hematoma was noted (r=0.687,P＜0.05). Liner positive correlations between the AQP4 expression level and both signal intensity ratio of T2WI and FLAIR sequences in the cerebral edema region were also found (r=0.640, 0.662; P＜0.05).Conclusion AQP4 has a close relation with the formation and expansion of hemorrhagic cerebral edema; over-expression of AQP4 may promote the formation of edema after intracerebral hemorrhage.