金属锰(Ⅱ)配合物的合成及高选择性检测硝基化合物的性质

Coordination polymers based on Mn(Ⅱ) and BPNO with selective and recyclable sensing of nitroaromatics

在室温扩散或溶剂热条件下,Mn(OAc)_2·4H_2O和N,N′-二氧化-4,4′-联吡啶(BPNO)分别与1,4-萘二酸(1,4-H2NDC)或5-氨基间苯二甲酸(NH_2-H_2BDC)反应,分离得到3个配位聚合物[Mn_2(1,4-NDC)_2(BPNO)_2(H_2O)_6·(BPNO)_3]_n(1),[Mn_2(BPNO)(1,4-NDC)_2·MeOH]_n(2)和[Mn_2(NH_2-BDC)_2(BPNO)(DMF)_2]_n(3).对这些化合物进行了红外、元素分析、热重、粉末X线衍射、单晶X射线衍射等表征.其中,化合物3在乙腈溶液中有着较好的稳定性和良好的荧光性质,可用来检测硝基类芳香化合物,它对检测2,4-DNP有着很高的选择性,并可循环使用.

Detection of nitroaromatic compounds as both potential explosives and environmental pollutants is important for national homeland security,environmental protection or military applications. Current detection methods are based on some sophisticated instruments including energy dispersive X-ray diffraction,gas chromatography coupled with mass spectrometry,nuclear quadrupole resonance,surface enhanced Raman spectroscopy,neutron activation analysis,electron capture detection,and cyclic voltammetry. These instruments are very expensive and not easily accessible in most conditions. As a simpler,quicker and less expensive method,the sensitive optical detection could potentially be widely employed. The coordination polymers（CPs） could be efficiently modulated by both analyte-metal and analyte-ligand interactions. Thus the CP-based fluorescent detection of nitro-explosives displays fast,sensitive and reversible compared with other methods. It is necessary to rationally design and synthesize appropriate ligands to prepare the stable and bifunctional CPs. In this work,three Mn（Ⅱ） coordination polymers [Mn_2（1,4-NDC）_2（BPNO）_2（H_2O）6·（BPNO）_3]_n（1,1,4-H_2NDC=1,4-naphthalenedicarboxylic acid,BPNO=1,2-Bis（4-pyridyl）-N,N′-dioxide）,[Mn_2（BPNO）（1,4-NDC）_2· MeOH]n（_2） and [Mn_2（NH_2-BDC）_2（BPNO）（DMF）_2]_n（3,NH_2-H_2BDC=5-aminoisophthalic acid） have been synthesized by the diffusion or solvothermal reactions of Mn（Ⅱ） salt with BPNO and 1,4-H2 NDC or NH_2-H_2 BDC. Complexes 1-3 were characterized by IR,elemental analysis,thermogravimetric analysis（TGA）,single crystal X-ray diffraction and powder X-ray diffraction（PXRD）. For compound 1,the [Mn（BPNO）（H_2O）_3] unit is connected by 1,4-NDC ligands to yield a 1D chain. For compound 2,a Mn（Ⅱ） center is bridged by two BPNO and four 1,4-NDC ligands to generate a 3D framework. For compound 3,the [Mn（DMF）] unit is connected by NH2-BDC and BPNO ligands to form a 2D network. Among them,compound 3 shows relatively strong emission at 507 nm in the solid state when excited at 370 nm at ambient temperature. A dispersed suspension of compound 3 in MeC N also exhibits relatively strong luminescent emission. This emission can be selectively quenched by nitroaromatics in MeC N with good sensitivity. We choose compound 3 to detect 2,4-DNP,4-nitroaniline,4-nitrophenol and nitrobenzene in MeC N. The results show that compound 3 possesses higher selective and recyclable sensing of 2,4-DNP among four nitroaromatics and could be a good candidate for the detection of nitroaromatics.