The investigation of third-order nonlinear optical (NLO) properties of coordination polymers (CPs) based on solid samples is very difficult but is crucial for practical applications. Herein, we show a method for preparing high optical quality CP films in a polymer matrix to study the third-order NLO performance of solid-state CPs. Two novel azobenzene-based CPs, [CdL­(DMAc)­(H2O)] n (1) and {[CuL­(4,4′-azobpy)]·3H2O} n (2) (H2L = 5-((4-(phenyldiazenyl)­phenoxy)­methyl)­isophthalic acid), were selected as study subjects. The corresponding microcrystals with a grain size of around 3 μm were doped into poly­(vinyl alcohol) (PVA), forming CP films (1-MC/PVA and 2-MC/PVA). 1-MC/PVA and 2-MC/PVA exhibit NLO absorption switching behavior from saturable absorption (SA) to reverse saturable absorption (RSA) with increasing pulse energy. Moreover, their NLO properties can also be efficiently modulated by photostimulation energy due to the trans → cis isomerization of an azobenzene moiety. The density functional theory (DFT) results show that the narrower the band gap between the conduction band minimum and the valence band maximum, the denser the electron density distribution in the central mental and coordination atoms, which is beneficial to exhibit better third-order NLO performance. This work provides a feasible method for the wider practical application of solid materials with excellent third-order NLO performance.

For studying the effect of a substituted group on the photoresponsive third-order nonlinear-optical (NLO) properties, photosensitive azobenzene derivative. Then H 2 L2 with a substituted methyl on the azobenzene ring was used to constructWhen the azobenzene moiety of the complexes is trans, the NLO behaviors of the complexes are the same. However, after the azobenzene moiety is excited by ultraviolet (UV) light to change from trans to cis, the substituted methyl increases the repulsion between two azobenzene rings in 3 and 4, thereby affecting their NLO behaviors. Therefore, the nonlinearity of the two types of complexes is different after UV irradiation. Density functional theory calculations support this result. The substituted methyl has a significant influence on the nonlinear absorption behaviors of 3 and 4. This work not only reports the examples of photoresponsive NLO materials based on metal complexes but also provides a new idea to deeply explore NLO properties.

Changing the chemical composition and generating heterogeneous structures have a synergistic effect on the third‐order nonlinear optical (NLO) properties of metal–organic frameworks (MOFs) materials. In this work, it is demonstrated that the transformations from a parent‐MOF [Zn4(dcpp)2(DMF)3(H2O)2]n (1, dcpp = 3,4‐bis(4‐carboxyphenyl)phthalate) into two child‐MOFs, [Cu4(dcpp)2(DMF)3(H2O)2]n (2) or [Zn2.5Co1.5(dcpp)2(DMF)3(H2O)2]n (3), via central metal exchange can regulate the third‐order NLO properties of the parent‐MOF, especially its third‐order NLO absorption signal can change from the reverse saturable absorption (RSA) to the saturable absorption (SA) when Cu2+ are introduced. Heterogeneous 1@CeO2 materials are further engineered by depositing CeO2 nanospheres onto the whole surface of 1, and are surprisingly still able to be exchanged into 2@CeO2 or 3@CeO2. Analyses on these MOFs@CeO2 indicate that the interfacial interaction between metal oxide particles and MOFs surface can effectively tune the charge transfer efficiency of the material which leads to their third‐order NLO refraction signals. The interface inducement of CeO2‐shell to the MOF‐core also significantly changes their third‐order NLO properties compared to pure MOFs. This work provides new insights and efficient strategies for the development of new third‐order NLO materials with potential practical usage.

Hg 2+ pollution seriously harms human life and health, and it is of great significance to develop Hg 2+ removal materials with excellent performance. In this work, a crystalline coordination polymer material {[Zn(L)(A)]•DMF} n (1) with 4.8 mmol/g amino loading density was engineered by using amino-functionalized ligands. Strong coordination properties of isonicotinic acid and adenine endow 1 with excellent chemical stability and thermal stability. Results of the removal experiment showed that 1 could efficiently remove >96% Hg 2+ within 10 min, and the saturated adsorption amount was 273 mg/g, which shows advantages over most reported MOF adsorbents. After combining IR spectra, XPS spectra, and CO 2 adsorption results, displacement of the characteristic peak demonstrated that the excellent capture performance is mainly attributed to the coordination interaction between high-density amino groups and Hg 2+ . This work provides a new consideration for the practical application of MOF adsorbents.

Photocatalytic reduction of CO 2 to value-added chemicals is known to be a promising approach for CO 2 conversion. The design and preparation of ideal photocatalysts for CO 2 conversion are of pivotal significance for the sustainable development of the whole society. In this work, we integrated two functional organic linkers to prepare a novel metal organic framework (MOF) photocatalyst {[Co(9,10-bis(4-pyridyl)anthracene) 0.5 (bpda)]•4DMF} (Co-MOF). The existence of anthryl and amino groups leads to a wide range of visible light absorption and efficient separation of photogenerated electrons. To extend the lifetime of photogenerated electrons in the photocatalytic system, we modified Co-MOF particles onto g-C 3 N 4 . As expected, Co-MOF/g-C 3 N 4 composites exhibited an ultrahigh selectivity (more than 97%) in the photocatalytic process, and the highest CO production rate (1824 μmol/g/h) was 7.1 and 27.2 times of Co-MOFs and g-C 3 N 4 , respectively. What's more, we also discussed the reaction mechanism of the Co-MOF/g-C 3 N 4 photocatalytic CO 2 reduction, and this work paves the pathway for designing photocatalysts with ideal CO 2 reduction performance.