The magnesium hydrate microsphere with large surface area was prepared by a facile and efficient template method. The products were characterised by transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis-differential scanning calorimetry, etc. The possible mechanism of Mg(OH) 2 assembled microsphere formation was discussed. In addition, the Mg(OH) 2 assembled microspheres were used as carried materials to assemble Mg(OH) 2 /ZAO nanocomposite catalysts. The degradation efficiency for Rhodamine B was increased by 35?7% compared with the performance of monoaluminium doped zinc oxide (ZAO) nanoparticles. At the same time, the Mg(OH) 2 /ZAO nanocomposite catalyst can be separated and recycled more easily than mono-ZAO nanoparticles.
Source of materialThe precursor compound 25,27-dihydroxy-26,28-dimethoxycalix[4]arene was obtained according to [1]. Then the compound was brominated with N-bromosuccinimide (NBS) in the molar ratio of 1:9 in butanone at room temperature. After reacting for three days, the title compound was obtained and recrystallized from chloroform/methanol.
Experimental detailsThe small N gt /N param ratio and the large R1 value are caused by the poor quality of the crystals.
DiscussionThe . We recently synthesized a new tetrabromo calix[4]-arene, which has two phenoxyl and two methoxyl groups, with complete bromination on the para position. The molecular structure of the title compound displays approximate twofold symmetry. Two kinds of hydrogen bonds exist in the crystal structure. One is the intermolecular hydrogen bond between O2 and Br3 i , which distance is 3.25 Å. Another one is the intramolecular hydrogen bonding between two hydroxyl and two methoxy groups at the lower rim, where the distances are 2.61 Å for O1···O2, 2.85 Å for O2···O3, 2.68 Å for O3···O4, and 2.95 Å for O4···O1. Therefore the cone conformation of the calix[4]-arene cavity is retained and pinched due to the intramolecular hydrogen bonds. The angles are 76.9°for ÐO4···O1···O2, 103.9°f or ÐO1···O2···O3, 77.6°for ÐO2···O3···O4, and 99.8°for ÐO3···O4···O1. The four dihedral angles are 116.6°, 130.7°, 114.9°, and 126.4°for the respective phenyl rings of C2C7, C9C14, C16C21, and C2328 to the reference plane defined by the bridging C atoms. The distances from C1, C8, C15 and C22 to the reference plane are 0.083 Å, 0.081 Å, 0.079 Å and 0.080 Å, respectively.
Source of materialThe title compound was prepared starting from the precursor compound 5,11,17,23-tetrabromo-25,26,27,28-tetrapropoxycalix[4]arene, which was obtained according to [1], in a similar one-step procedure as described in [2] and recrystallized from chloroform/methanol. The molecule in the crystal structure of the title compound displays non-crystallographic twofold symmetry. The cone conformation of the calix[4]arene cavity is retained from the precursor, but pinched due to the two OH···N hydrogen bonds between the two N-tert-butylhydroxyamine groups on the upper rims. The hydrogen bond lengths are 2.07 Å for H3A···N2 and 2.04 Å for H6A···N1, and the angles are 150.8°for ÐO3H3A···N2 and 151.9°for ÐO6H6A···N1. The two dihedral angles are 75.5°for the phenyl ring C9 C14 and 146.0°for the phenyl ring C2 C7 to the reference plane of the bridging C atoms (here C1, C8 and their equivalents). The distances between centroids for the two symmetry-equivalent phenyl rings are 4.60 Å for ring C9 C14 and its equivalent, and 7.78 Å for ring C2 C7 and its equivalent.
Discussion
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