The building block modular approach that lies behind coordination polymers (CPs) and metal-organic frameworks (MOFs) results not only in a plethora of materials that can be obtained but also in a vast array of material properties that could be aimed at. Optical properties appear to be particularly predetermined by the character of individual structural units and by the intricate interplay between them. Indeed, the "design principles" shaping the optical properties of these materials seem to be well explored for luminescence and second-harmonic generation (SHG) phenomena; these have been covered in numerous previous reviews. Herein, we shine light on CPs and MOFs as optical media for state-of-the-art photonic phenomena such as multi-photon absorption, triplet-triplet annihilation (TTA) and stimulated emission. In the first part of this review we focus on the nonlinear optical (NLO) properties of CPs and MOFs, with a closer look at the two-photon absorption property. We discuss the scope of applicability of most commonly used measurement techniques (Z-scan and two-photon excited fluorescence (TPEF)) that can be applied for proper determination of the NLO properties of these materials; in particular, we suggest recommendations for their use, along with a discussion of the best reporting practices of NLO parameters. We also outline design principles, employing both intramolecular and intermolecular strategies, that are necessary for maximizing the NLO response. A review of recent literature on two-, three- and multi-photon absorption in CPs and MOFs is further supplemented with application-oriented processes such as two-photon 3D patterning and data storage. Additionally, we provide an overview of the latest achievements in the field of frequency doubling (SHG) and tripling (third-harmonic generation, THG) in these materials. Apart from nonlinear processes, in the next sections we also target the photonic properties of MOFs that benefit from their porosity, and resulting from this their ability to serve as containers for optically-active molecules. Thus, we survey dye@MOF composites as novel media in which efficient upconversion via triplet energy migration (TEM) occurs as well as materials for stimulated emission and multi-photon pumped lasing. Prospects for producing lasing as an intrinsic property of MOFs has also been discussed. Overall, further development of the optical processes highlighted herein should allow for realization of various photonic, data storage, biomedical and optoelectronic applications.

Stimulated emission as the new intrinsic property of metal-organic frameworks is demonstrated in article number 1605637 by Roland A. Fischer and co-workers, by the observation of stimulated emission peak, and time-resolved photoluminescence, along with the support of density of state calculations. The results identify that immobilization of strong luminescent chromophores between the metal-nodes leads to the formation of the materials with enhanced stability and optical behavior for the next generation solid-state lasers. Dual-Ion Batteries In article number 1606805, Yongbing Tang and co-workers report a bubble-sheet-like aluminum foil used as anode and current collector in a dual-ion battery. This novel structure helps guide the Al-Li alloying position and confines the volumetric change, and thus results in excellent long-term cycling stability, featuring 99% capacity retention within 1500 cycles at 2 C. Ionic-Liquid Gating Ionic-liquid-gating control of interfacial magnetic aniso-tropy in Au/[DEME]+[TFSI]-/Co/SiO 2 multilayer structures is quantitatively determined by the electron spin resonance method, as described in article number 1606478 by Ziyao Zhou, Ming Liu and co-workers. A reproducible, reversible ferromagnetic resonance field shift of 219 Oe at an applied voltage of 1.5 V, with a large ME tunability of 146 Oe V −1 , is achieved, assisted by the electric double layers at the room temperature. Magnetic Memory In article number 1606748, Yossi Paltiel and co-workers use 30-50 nm ferromagnetic nanoplatelets (FMNPs) on top of an organic chiral molecule monolayer to demonstrate nano-based magnetless magnetic memory device at ambient temperatures. The memory is based on the chiral induced spin selectivity effect. This technology could make it possible to create inexpensive, high-density universal memory devices with much lower power consumption than existing technologies. Additive Manufacturing of Metal Structures at the Micrometer Scale To enable the additive manufacturing of metals at the micrometer scale, a variety of novel techniques are currently in use. The individual techniques are introduced, detailing their underlying principles. Furthermore, it critically compares their fabrication capabilities, in particular the minimum feature size, achievable geometry and obtained materials properties. Blue-color stimulated emission with low threshold power is observed from In-and Zn-MOFs, which feature a highly fluorescent chromophore densely packed and rigidly linked to the metal-ion centers in the solid state. The density-of-states and transition dipole moments are calculated and the stimulated emission phenomenon is correlated with these properties. Dual-Ion Batteries A bubble-sheet-like aluminum foil is developed and used as anode material and current collector in a dual-ion battery (DIB). This novel structure helps guide the AlLi alloying position within the hollow nano-spheres and confines the alloy sizes. As a result, this design significantly relieves the volumetric change, and thus maintains ultrasta...

Coordination polymers show great potential for the tailored design of advanced photonic applications by employing crystal chemistry concepts. One challenge for achieving a rational design of nonlinear optically active MOF materials is deriving fundamental structure–property relations of the interplay between the photonic properties and the spatial arrangements of optically active chromophores within the network. We here investigate two-photon-absorption (TPA)-induced photoluminescence of two new MOFs based on a donor–acceptor tetraphenylphenylenediamine (tPPD) chromophore linker (H4TPBD) and Zn­(II) and Cd­(II) as metal centers. The TPA efficiencies are controlled by the network topologies, degree of interpenetration, packing densities, and the specific spatial arrangement of the chromophores. The effects can be rationalized within the framework of established excited-state theories of molecular crystals. The results presented here demonstrate the key effect of chromophore orientation on the nonlinear optical properties of crystalline network compounds and allow for establishing quantitative design principles for efficient TPA materials.

The formation of different conformers of dinuclear silver(i) and gold(i) 1,1'-(2-hydroxyethane-1,1-diyl) bridge-functionalized bis(NHC) complexes with various wing-tip substituents (R = methyl, isopropyl and mesityl) has been investigated using multinuclear NMR spectroscopy and SC-XRD as well as DFT calculations. The ratio of anti/syn isomers strongly depends both on wing-tip substituents and the metal. Moreover, the reaction temperature plays a significant role during the transmetallation process for the ratio of gold(i) conformers, which is further affected by purification procedures. All obtained Au(i)-bis(NHC) complexes have been applied in a standard MTT assay performed for screening the antiproliferative activity against human lung and liver cancer cells. Strong evidence for a significant influence of both wing-tip substituents and conformation on the cytotoxic properties of the applied complexes has been found.