FULL PAPER © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1 wileyonlinelibrary.com 1. Introduction Detecting the concentration of oxygen is of great practical sig- nificance, [1] and high-sensitivity sensors are highly demanded for trace oxygen analyses in many environments that must be oxygen- free such as metallurgy, chemical industry, and so on. [2] Optical Porous Cu(I) Triazolate Framework and Derived Hybrid Membrane with Exceptionally High Sensing Efficiency for Gaseous Oxygen Si-Yang Liu, Xiao-Lin Qi, Rui-Biao Lin, Xiao-Ning Cheng, Pei-Qin Liao, Jie-Peng Zhang,* and Xiao-Ming Chen Phosphorescent complexes of precious metal ions are widely studied as optical sensing materials for molecular oxygen. Combining the advan- tages of luminescent complexes and porous matrixes, porous coordination polymers show great potential for oxygen-sensing, although their sensitivity, requirement of precious metal, and device fabrication remain challenging issues. In this work, the photoluminescence and oxygen-sensing proper- ties of the porous Cu(I) triazolate framework [Cu(detz)] (MAF-2, Hdetz = 3,5-diethyl-1,2,4-trizole) is studied in detail, which shows high chemical stability in moisture and water, very long phosphorescent lifetime (116 μs) and large Stokes shift (14562 cm -1 ), as well as considerable oxygen permeability (1.7 × 10 -11 mol cm -1 s -1 bar -1 ) at ambient conditions, giving rise to exceptionally high luminescence quenching efficiency of 99.7% at 1 bar O 2 ( I 0 / I 100 = 356) with a perfectly linear Stern-Volmer plot ( K SV = 356 bar -1 , R 2 = 0.9998), fast response and good reversibility. Further, a counter-diffusion crystal-growth method was developed to fabricate MAF-2 thin films protected by silicone rubbers as the first example of soft membrane oxygen sensor based on coordination polymer or metal-organic framework, which exhibited extraordinary oxygen-sensing performance (limit of detection = 0.047 mbar) and outstanding mechanical property, as well as outstanding chemical sta- bility even in an acidic atmosphere. DOI: 10.1002/adfm.201401125 S.-Y. Liu, Dr. X.-L. Qi, R.-B. Lin, P.-Q. Liao, Prof. Dr. J.-P. Zhang, Prof. Dr. X.-M. Chen MOE Key Laboratory of Bioinorganic and Synthetic Chemistry State Key Laboratory of Optoelectronic Materials and Technologies School of Chemistry and Chemical Engineering Sun Yat-Sen University Guangzhou 510275, China E-mail: zhangjp7@mail.sysu.edu.cn Dr. X.-N. Cheng Instrumental Analysis and Research Center Sun Yat-Sen University Guangzhou 510275, China oxygen sensors based on luminescence quenching have attracted a great deal of attention for their high sensitivity and capa- bility of online detections and non-invasion measurements. [3] To fabricate a lumines- cence sensor, luminescent dyes should be immobilized on gas-permeable substrates, most of which are in the membrane form. [4] It is worth pointing out that oxygen-sensing luminescent dyes usually perform very dif- ferently in the solution, bulk-solid, and thin- film states, [5] and most sensing compounds have never become sensors. [3] Although some florescent materials have demonstrated high oxygen-sensing efficiencies, [6] phosphorescent dyes, espe- cially coordination complexes of precious metal ions (Pt, Ru, Au, Ir, Re, etc.), are still the most preferred choices for lumines- cent sensing, [7] because phosphorescence based on triplet excited state has high quantum yield and luminescent intensity (for high sensitivity), long lifetime (for reducing the interference from scattered light and fluorescence background, by using time-resolved luminescence meas- urement), and large Stokes shift (for easy separation of excitation and emission). [8] Porous coordination polymers (PCPs) are highly ordered arrays of metal complexes containing guest-accessible chan- nels. [9] Various functionalities, such as luminescent building blocks, can be rationally incorporated into PCPs. [10] By virtue of their diverse and tunable structures, luminescent PCPs have emerged as promising sensing materials for solvent, vapor, and ion species. [11] Recently, a few oxygen-sensing PCPs have been reported, which are mostly based on phosphorescent Ru(II) or Ir(III) metalloligands. [12] So far, it is still very challenging to reduce the precious metal content and increase the oxygen- sensitivity of luminescent PCPs. [6] In addition, bulk PCP crys- tals cannot be used directly in practical applications, especially as gas sensors. The loose powders are difficult to handle as a sensor unless they are processed or molded into applicable configurations such as membranes. [13] Unlike molecular and macromolecular luminescent dyes, PCPs are generally fragile, crystalline and insoluble materials, which can be hardly made into soft membrane devices for sensing. [14] Adv. Funct. Mater. 2014, DOI: 10.1002/adfm.201401125 www.afm-journal.de www.MaterialsViews.com