[A new guaiane-type sesquiterpenoid from Croton yunnanensis].

Five sesquiterpenoids were isolated from 90% ethanol extract of Croton yunnanensis by silica gel,Sephadex LH-20 column chromatography,as well as prep-HPLC methods. Based on MS,1 D and 2 D NMR spectral analyses,the structures of the five compounds were identified as 11-methoxyl alismol(1),6ß,7ß-epoxy-4α-hydroxyguaian-10-ene(orientalol C,2),multisalactone D(3),arvestonol(4),and 4,5-dihydroblumenol A(5). Compound 1 was a new guaiane-type sesquiterpenoid. Compounds 2-4 were isolated from the Croton genus for the first time,and compound 5 was obtained from this plant for the first time.

Methyl 3-amino-but-2-enoate.

The title compound, C(5)H(9)NO(2), is almost planar (r.m.s. deviation for the non-H atoms = 0.036 Å) and an intra-molecular N-H⋯O hydrogen bond generates an S(6) ring. In the crystal, N-H⋯O inter-actions link the mol-ecules into C(6) chains propagating along [010].

Bioactive glycosides from Salacia cochinchinensis.

Four new triterpene glycosides, named salaciacochinosides A-D (1-4) were isolated from the 90% ethanol extract of Salacia cochinchinensis, together with five known compounds 2α,3ß,23-trihydroxyurs-12,18-dien-28-oic acid 28-O-ß-d-glucopyranoside (5), racemiside (6), alangiplatanoside (7), acantrifoside E (8), and syringin (9). The structures of the four new triterpenoids were characterized by chemical methods and MS, IR, 1D and 2D NMR spectral analyses. The α-glucosidase inhibitory activities of the nine compounds were assessed, compounds 6 and 7 showed remarkable α-glucosidase inhibitory activities, with IC50 values of 0.44 and 0.75 µM, respectively. Compounds 1-5 exhibited moderate α-glucosidase inhibitory activities, and compounds 8 and 9 showed none α-glucosidase inhibitory activity in our current experiments.

[(2-{[3',6'-Bis(ethyl-amino)-2',7'-dimethyl-3-oxospiro-[1H-isoindole-1,9'-9H-xanthen]-2-yl}eth-yl)amino-meth-yl]phenol.

The title compound, C(35)H(38)N(4)O(3), was prepared as a spiro-lactam ring formation of rhodamine dye for comparison with a ring-opened form. The xanthene ring system is approximately planar. The dihedral angles formed by the spiro-lactam and phenol rings with the xanthene ring system are 85.7 and 109.4°, respectively. Each of the mol-ecules in the crystal structure contains one intra-molecular O-H⋯N hydrogen bond, and they form inter-molecular N-H⋯O hydrogen-bonded chains along the [100] direction. Weak inter-molecular C-H⋯O hydrogen-bonding contacts connect the infinite chains via crystallographic inversion centres to form a two-dimensional network.

Erratum: [(2-{[3',6'-Bis(ethyl-amino)-2',7'-dimethyl-3-oxospiro-[1H-isoindole-1,9'-9H-xanthen]-2-yl}eth-yl)amino-meth-yl]phenol. Corrigendum.

The title and the chemical diagram of the paper by Zhang, Peng, Gao & Fan [Acta Cryst. (2008), E64, o403] are corrected.[This corrects the article DOI: 10.1107/S1600536807055559.].

A Sr2+-metal-organic framework with high chemical stability: synthesis, crystal structure and photoluminescence property.

Metal-organic frameworks (MOFs) are typically built by assembly of metal centres and organic linkers, and have emerged as promising crystalline materials in a variety of fields. However, the stability of MOFs is a key limitation for their practical applications. Herein, we report a novel Sr 2+: -MOF [Sr4(Tdada)2(H2O)3(DMF)2] (denoted as NKU- 105: , NKU = Nankai University; H4Tdada = 5,5'-((thiophene-2,5-dicar bonyl)bis(azanediyl))diisophthalic acid; DMF = N,N-dimethylformamide) featuring an open square channel of about 6 Šalong the c-axis. Notably, NKU- 105: exhibits much outstanding chemical stability against common organic solvents, boiling water, acids and bases, relative to most MOF materials. Furthermore, NKU- 105: is an environment-friendly luminescent material with a bright cyan emission.This article is part of the themed issue 'Coordination polymers and metal-organic frameworks: materials by design'.

[Effects on phenol removal in the process of enhanced coagulation by manganese dioxide formed in situ].

Phenol was selected as a model compound. Factors, such as Ca2+, tannic acid, dose of kaolinite, dose of manganese dioxide formed in situ and pH, were invested on phenol removal in the process of enhanced coagulation by manganese dioxide formed in situ. Results showed that the addition of Ca2+ is beneficial for phenol removal. In the range of Ca2+ varied from 0 to 1.0 mmol x L(-1), the efficiency of phenol removal was enhanced more than 10%. Tannic acid can enhance phenol removal significantly when they are coexisted in water. As tannic acid was added to 10 mg x L(-1), phenol removal can be increased about 30% and 50% in the process of coagulation by AlCl3 and enhanced coagulation by manganese dioxide formed in situ, respectively. The dose of coagulant can be reduced in the process of enhanced coagulation with the addition of manganese dioxide formed in situ. The point of 1 mg x L(-1) manganese dioxide formed in situ linked with 30 mg x L(-1) AlCl3 can have the same phenol removal efficiency as the addition of 50 mg x L(-1) AlCl3. In the range of pH varied from 5 to 9, phenol can be removed with the high efficiency in the process of enhanced coagulation by manganese dioxide formed in situ. While under the strong acid condition and strong basic condition, phenol has lower removal efficiency.

[Influence of catalytic ozonation process on suppressing bromate formation potential in drinking water treatment].

An investigation is given to the bromate formation of catalytic ozonation in treating drinking water. It is shown that the c x t value of ozone depletion stage plays a more important role in BrO3(-) formation. Catalyst addition not only reduces the residual ozone content by 60.0% - 77.4% but also extends the ozone ID stage time from 4.3 min to 6.8 min, which makes the ozone c x t value shorter. A full-scale study indicates a very effective strength and performance of catalytic ozonation in controlling BrO3(-) formation and it is able to suppress BrO3(-) formation potential by 51.7% on average.

[Study on mechanism of phenol oxidized by fresh manganese dioxide in aqueous].

pH is the key factor to affect reaction process. Adsorption and redox take place at pH > or =4 and pH <4, respectively. Free-radical and Mn3+ was inferred to produce and participate in reaction at pH <4. The oxidizing products of phenol are p-benzoquinone and biphenol determined by GC-MS. The efficiency of phenol and soluble manganese as a function of time and temperature were examined at pH <4 in order to test the mechanism inferred. Results show removal percents of phenol increase from 65% to 95% with time varied from 10 min to 70 min, but soluble manganese changes little. Removal percents of phenol increase with temperature also, but soluble manganese doesn't change. This means fresh manganese dioxide is not the only oxidant in aqueous and other oxidant , i.e. Mn34+, appears during the reaction. High valence cation, i.e. Al3+, promoted the removal percent of phenol while anion, i.e. PO4(3-), decrease the efficiency of phehol.