A new lanthanide citrate coordination polymer [Dy(citrate)(H2O)]n (1) was hydrothermally synthesized and structurally characterized by elemental analyses, single-crystal X-ray diffraction, IR spectroscopy, thermogravimetric analysis, photoluminescence spectrum, and magnetic measurements. The structure of 1 exhibits a 2D layer structure, in which the Dy2O2 dimer serves as the building block. The photoluminescence spectrum shows blue luminescence in the solid state at room temperature. Owing to the special frustration structure, unusual magnetic relaxation was found in compound 1. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Unusual Magnetic Behavior of a 2D Citrate‐Bridged Dysprosium(III) Coordination Polymer

The structures and chemistry of 1,3-oxazine derivatives and their carbo- or heterocycle-fused analogs have been studied thoroughly from various aspects in recent decades. Numerous methods have been devised for the preparation of the variously saturated or substituted derivatives of this family of heterocycles, and are discussed in this chapter with regard to the mode of assembly of the ring atoms. The latest developments in these fields, involving multicomponent reactions, solid-phase procedures, and both conventional and enzymatic catalytic methods of synthetic organic chemistry, allow the highly regio-, stereo-, and enantioselective preparation of these compounds. With the increasing demand for chiral nonracemic molecules, stereoselective methods for the synthesis of 1,3-oxazine derivatives and applications of enantiopure 1,3-oxazines in asymmetric transformations have recently gained in importance. The wide-ranging possibilities for the application of 1,3-oxazine derivatives in organic syntheses have been utilized in the preparation of numerous mono- or difunctional compounds, including key intermediates toward natural products or bioactive substances. Besides the structural and chemical characterization of 1,3-oxazines and their carbo- or heterocycle-fused analogs, their most important biologically active derivatives are also discussed.

1,3-Oxazines and their Benzo Derivatives

The absolute configuration of the title compound, C20H26BrNO3, was determined from both the synthetic precursor and anomalous scattering effects. In the crystal structure, non-classical C—H⋯O hydrogen bonds link the mol­ecules into a sheet parallel to the b axis.

(1′S,2′S,5′R)‐3‐(2‐Bromo­propion­yl)‐2′‐isopropyl‐5′‐methyl­spiro­[2H‐1,3‐benzoxazine‐2,1′‐cyclo­hexa­n]‐4(3H)‐one

The title compound, C22H26N3O, crystallizes in space group P21 with two mol­ecules in the asymmetric unit. Intermolecular N—H⋯O hydrogen bonds play an important role in the formation of polymeric chains running along the crystallographic a axis.

Qing Yuan

Papers

(1′S,2′S,5′R)‐3‐(2‐Bromopropionyl)‐2′‐isopropyl‐5′‐methylspiro[2H‐1,3‐benzoxazine‐2,1′‐cyclohexan]‐4(3H)‐one

4‐(9‐Acridin‐9‐ylamino)‐2,2,6,6‐tetramethylpiperidine N‐oxide

Qing Yuan

Papers

(1′S,2′S,5′R)‐3‐(2‐Bromo­propion­yl)‐2′‐isopropyl‐5′‐methyl­spiro­[2H‐1,3‐benzoxazine‐2,1′‐cyclo­hexa­n]‐4(3H)‐one

4‐(9‐Acridin‐9‐yl­amino)‐2,2,6,6‐tetra­methyl­piperidine N‐oxide

(1′S,2′S,5′R)‐3‐(2‐Bromopropionyl)‐2′‐isopropyl‐5′‐methylspiro[2H‐1,3‐benzoxazine‐2,1′‐cyclohexan]‐4(3H)‐one

4‐(9‐Acridin‐9‐ylamino)‐2,2,6,6‐tetramethylpiperidine N‐oxide