Synthesis, Structure and Luminescent Properties of a New Terbium(Ⅲ) Complex with 5-B

Synthesis,Structure and Luminescent Properties of

a New Terbium(III) Complex with 5-Bromoisophthalic Acid①

LIU Guang-Xiang② ZHA Xiao-Chun LI Xing-Long

【摘 要】ABSTRACT The self-assembly of 5-bromoisophthalic acid (H2BIPA) with Tb(NO3)3·6H2O under hydrothermal conditions gives rise to a 3D coordination polymer,[Tb2(BIPA)3(CH3CH2OH)]n(1),which was characterized by elemental analysis,IR and single-crystal X-ray diffraction.The crystal is of monoclinic system,space group P21/c with a=19.2591(17),b=8.2537(7),c=18.5663(17) ?,β=104.4720(10)°,V=2857.6(4)

?3,C26H15Br3O13Tb2,Mr=1092.95,Dc=2.540

g/cm3,F(000)=2040,μ=9.173 mm-1 and Z=4.The final R=0.0324 and wR=0.0767 for 5299 observed reflections (I >2σ(I)).Complex 1 displays an

unusual

three-dimensional

(4,6)-connected

is

network different

with from

(48.66.8)2(44.62)2(42.84) topology,which

[Tb(HBDC)(BDC)(H2O)4]·3.3H2O (BDC=isophthalate) because the -Br substituent of isophthalate results in different electronic effect and steric hindrance to change the coordination modes of carboxylate groups in the assembly process.Moreover,luminescent properties of 1 have also been investigated in the solid state. 【期刊名称】结构化学

【年(卷),期】2012(031)002 【总页数】6

【关键词】Keywords: Tb(III) coordination polymer,crystal structure,5-bromoisophthalic acid,luminescence

1 INTRODUCTION

There is currently a great deal of interest in the design and construction of metal-organic frameworks (MOFs) created by joining the metal centers with organic linkers because of their intriguing structural topologies and versatile applications in the areas of redox catalysis,ion exchange,adsorption,separation,sensors,magnetism

and

photoluminescence[1-6].The pivotal point for the design and synthesis of desirable structures with functional properties heavily depends on the judicious choice and assembly of metal centers with the organic bridging ligands[7-9].The lanthanide ions are extensively employed as building blocks to construct MOFs which exhibit fascinating architectures due to their high and variable coordination numbers and flexible coordination geometry[10-13].More importantly,lanthanide ions often endow the MOFs with unique magnetism and luminescent properties.

With respect to luminescence,the emissions from near infrared (NIR) radiation to blue light of different lanthanide ions make them of interest for a range of applications.Among the lanthanide ions,Tb(III) ion is one

of the most important elements to be used as optical centers.Tb(III) complexes are

attractive

for

its application in

the

visible

region[14].However,direct excitation of the 4f-4f transitions is difficult because of poor absorption abilities of lanthanides.Efficient excitation of the metal-cente-red luminescence has to rely on the energy transfer from the surroundings of lanthanide ion[15].Thus,the selection of a suitable ligand is crucial in building lanthanide coordination polymers.Isophthalic acid possesses excellent characteristics as follows: it has two carboxyl groups with four oxygen atoms which can be used for coordination;the skew coordination orientation of carboxyl groups should favor the formation of a helical structure[16-17] and its phenyl group having high structuring effect could act as efficient sensitizer for lanthanide emissions[15].For this purpose,we have chosen 5-bromoisophthalic acid (H2BIPA) as the organic ligand,while Tb(III)ion as the metal centers.Compared with isophthalate,the -Br substituent of isophthalate may result in different electronic effect and steric hindrance to change the coordination modes of carboxylate groups in the assembly process.Herein,we present the synthesis,structure and luminescent properties of a new three-dimensional coordination polymer 1.

2 EXPERIMENTAL

2.1 Materials and methods