News & ViewsMetal-organic framework microlasersYuan Liua , Haiyun Dong b , Fengqin Hu a, ⇑ , Yong Sheng Zhao b, ⇑a College of Chemistry, Beijing Normal University, Beijing 100875, Chinab Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, ChinaThe discovery and continued development of the lasers have ledto a revolution in both fundamental researches and optoelectronicindustry. Recently, micro/nanolasers that can generate intensecoherent light signals at (sub)wavelength scale have become aresearch focus due to their potential applications in a variety off i elds ranging from chemical and biological sensing to integratedoptoelectronic circuitry [1,2]. Organic materials are a kind of excel-lent gain media in fabricating high-performance miniaturizedlasers towards low threshold and broad tunability because of theirsuperiority in easy processing, large optical cross-sections, andwide emission band [3]. However, most organic materials usuallysuffer from aggregation-caused quenching (ACQ) and relativelypoor stability, which has hindered the further development ofthe organic micro/nanolaser f i eld.An effective strategy for avoiding ACQ is to incorporate theorganicdyemoleculesasguestintohostmatrices.WritinginNatureCommunications, Banglin Chen, Guodong Qian and co-workers [4]demonstrated a new type of microlasers based on dye-encapsu-latedmetal-organicframework(MOF) microcrystals [5].It is knownthat MOFs are a type of porous organic-inorganic hybrid coordina-tion polymers with high thermal and chemical stability. Due to thehighly regular channel structures and controllable pore sizes, theMOFs can serve as host materials for the encapsulation of guestfunctional molecules. In this work, the micrometer-sized rod-likesingle crystals of the anion porous bio-MOF-1 were synthesizedwith a solvothermal reaction. Then a cationic pyridiniumhemicya-nine dye, 4-[p-(dimethylamino)styryl]-1-methylpyridinium(DMASM), was packed into the MOF microcrystals via an ion-exchange process, as illustrated in Fig. 1a. The pore conf i nementeffect of bio-MOF-1 can spatially separate the organic dye mole-cules and thus minimize the ACQ effect. By virtue of regularlyshaped morphology and smooth surfaces, the bio-MOF-1 micro-crystals can serve as typical Fabry-Pérot (F-P) optical microcavity(Fig. 1b). Under two-photon pumping, a very stable laser outputwas achieved from the DMASM@bio-MOF-1 microcrystals (Fig. 1c).The arrangement of organic molecules has a great inf l uence onthe material optical properties, such as nonlinear optical propertiesand absorption/emission polarizations. MO materials have tunablepore sizes, which may make the dye molecules highly orientedwithin the framework and thus lead to some unique lasingproperties. As reported in Nature Communications, He et al. [6] fab-ricated a polarized frequency-upconversion dye@MOF microlasers.They selected a MOF (ZJU-68) with the size-matched width of dyemolecules (DMASM) and developed a one-pot solvothermalmethod for the synthesis of MOF, where the organic dye moleculeswere encapsulated in-situ during the solcothermal reaction. Highlyordered and oriented arrangement of dye molecules wereachieved, which contributed to a high-performance polarizedthree-photon-pumped lasing in the host/guest microcrystals. Thepolarized multi-photon-pumped microcrystal lasers may f i nd greatpotentials in practical applications of biological imaging and infor-mation storage.The variable micro-environment of MOF pores provides thepossibility for modulating the lasing performance with the envi-ronmentally responsive guest dye molecules. The intramolecularcharge transfer (ICT) dyes possess energy levels and excited-stateprocesses that are very sensitive to the surrounding environment[7]. In a communication published recently in Advanced Materials,our group constructed a type of wavelength-tunable microlaserFig. 1. (Color online) (a) Schematic illustration of the encapsulation of DMASM intobio-MOF-1. (b) Fluorescence microscopic images of DMASM@bio-MOF-1. (c) Lasingcharacteristics of DMASM@bio-MOF-1 under two-photon pumping. Reprinted bypermission from Macmillan Publishers Ltd: [Nature Communication] (Ref. [4]).http://dx.doi.org/10.1016/j.scib.2016.12.0022095-9273/? 2016 Science China Press. Published by Elsevier B.V. and Science China Press. All rights reserved.⇑ Corresponding authors.E-mail addresses: fqhu@bnu.edu.cn (F. Hu), yszhao@iccas.ac.cn (Y.S. Zhao).Science Bulletin 62 (2017) 3–4Contents lists available at ScienceDirectScience Bulletinjournal homepage: www.elsevier.com/locate/scib
