Preparation And Postsynthetic Modification Of Copper/Silver Based Coordination Polymers And Their Luminescent Detection Properties

Porous coordination polymers,with rich active groups,large specific surface area and adjustable pore structure,have attracted more and more attention due to their wide range of applications in ion exchange,fluorescence detection,adsorption and separation.Among them,fluorescence detection has been widely studied due to the advantages of high sensitivity,fast response speed,easy operation and good selectivity.However,coordination polymers synthesized directly cannot usually meet the desired requirements of the application.Through post-synthesis modification,porous coordination polymers can encapsulate fluorescent guests such as Ln³⁺ ions,dye molecules and quantum dots to design and synthesize ratiometric fluorescent probes.In this paper,we have successfully constructed eight novel copper/silver based coordination polymers.Based on the uncoordinated carboxylic acid,dual-emission fluorescent materials were prepared by encapsulating Ln³⁺ ions within coordination polymer through post-synthesis modification method.And the fluorescent detection of small biological molecules and pollutant ions have been also investigated.Firstly,a novel copper-based coordination polymer[Cu?cbpp??Hcbpp?]·3H2O?1,Hcbpp = 1-?4-carboxylbenzyl?-3-?pyrzin-2-yl??was successfully synthesized in the presence of reducing agent Na2SO3.The remained uncoordinated carboxylic acid groups provide an appropriate platform for the loading of Ln³⁺ ions.The composite Eu³⁺@1,prepared by postsynthetic modification,has dual emission characteristics at 485 nm and 616 nm,which can be attributed to the organic ligand Hcbpp and Eu³⁺,respectively.The rich active components and fluorescence characteristics make the composite Eu³⁺@1 have different fluorescence responses to H2 S,vitamin C and Fe2+.By using these chemical events as inputs and the different fluorescence of B485 and R616 as dual outputs,a series of multifunctional elementary logic operations?YES,NOT,XOR,IMP and INH?and integrative logic operation?XOR?INH?-OR?have been realized to perform non-arithmetic functions.In order to realize the selective detection of H2 S,two copper coordination polymers Cu?Hcpoc?2?2,H2 cpoc = 5-?4'-carboxyphenoxy?nicotinic acid?and Cu5?cpc?2?Hcpc?2?OH?4?3,H2 cpc = 5-?4'-carboxyphenyl?nicotinic acid?were successfully obtained.The carboxyl acid group,pointed to 1D channel?0.83 nm × 0.83 nm?,was not completely coordinated.It can be further binded with Tb³⁺ to prepare the composite Tb³⁺@2,which show excellent selectivity and sensitivity?1.20 ?mol?L-1?.It can meet the testing needs in actual biological samples?10-600 ?mol?L-1?.Thirdly,we further designed and synthesized a 2D heterometallic coordination polymer [Eu2Cu2?pydc?4?ox??H2O?6]·3H2O?4,H2 pydc = 2,3-pyridinedicarboxylic acid,ox = oxalic acid?.The framework exhibit 1D channels with the window size of approximately 1.01 nm ×1.46 nm,which is larger than the maximum sizes of vitamin C?0.70 nm?and H₂S?0.20 nm?.Excellent stability and uncoordinated saturation of metal ions make 4 as good fluorescent probe for H2 S and vitamin C detection.We also proposed the H2O2-4 fluorescence system for the first time,AA or/and H2 S as substrates as well as 4 as fluorescent indicator,H2O2 was added dropwise to oxidize AA or/and H2 S in turn to realize simultaneous,selective and quantitative detection in a wide range.Fourthly,two copper-based coordination polymers Cu Cl?cbpp??5?and Cu Cl2?Hcbpp??6?were designed and synthesized by changing the proportions of metal salts.It is showed that 6 has no fluorescence emmission.However,once the carboxyl group was completely deprotonized by simple acid-base reaction to generate Na+@6,the corresponding product showed ligand emission in the range of 340–450 nm.Furthermore,the composite Tb³⁺@6 was prepared through ion-exchange,which can act as a fluorescent probe for the metabolite NMF of DMF in organisms.Finally,one cationic coordination polymers [Ag5?Hcbpp?4?cbpp?2?NO3?]?2NO3?7?was prepared.The excellent water stability,high charge and open framework of 7 provide inherent advantages for the adsorption of Cl O4-anions.The experiment shows that 7 has a high adsorption capacity,and the maximum adsorption capacity is more than 108.70 mg?g-1.Importantly,7 shows obvious spatial confinement for Cl O4-anions,as confirmed,via a SC–SC approach.Meanwhile,the resultant 7 can be applied as a highly selective and sensitive fluorescent sensor for quantitative detection of Cl O4-anion,which has a lower detection limit?17.40 ?g?L-1?than the threshold value in drinking water?24.50 ?g?L-1?.