No abstract

We demonstrate herein a promising pathway towards low-energy CO2 capture and release triggered by UV and visible light. A photosensitive diarylethene ligand was used to construct a photochromic diarylethene metal-organic framework (DMOF). A local photochromic reaction originating from the framework movement induced by the photoswitchable diarylethene unit resulted in record CO2-desorption capacity of 75% under static irradiation and 76% under dynamic irradiation.

Reversible single-crystal-to-single-crystal transformation (SCSC) was for the first time observed between 4f-based molecular magnets.

We demonstrate herein a promising pathway towards low-energy CO 2 capture and release triggered by UV and visible light. A photosensitive diarylethene ligand was used to construct a photochromic diarylethene metal-organic framework (DMOF). A local photochromic reaction originating from the framework movement induced by the photoswitchable diarylethene unit resulted in record CO 2 -desorption capacity of 75 % under static irradiation and 76 % under dynamic irradiation.Diarylethene derivatives are one of the most promising families of photochromic compounds. They undergo photoinduced isomerization involving ring-opening/closing reactions triggered by UV and visible light, mainly as a result of their fatigue-resistant and thermally irreversible properties. They have potential for application in optoelectronic devices, such as ultrahigh-density optical data storage, logic gates, molecular wires, and sensors. [1][2][3] Diarylethene derivatives have been reported as switching materials, including fluorescent molecular switches, photochromic chiral switches, photocontrolled conductivity switches, and liquid-crystal switches. [4][5][6] The photostability of these derivatives was also found to be very high, with more than 10 4 photoinduced coloration/decoloration cycles and a lifetime of more than a thousand years at 30 8C. [2] Another family of compounds, metal-organic frameworks (MOFs), show unique potential as sorbents for CO 2 capture and release in view of their structurally designable nature and large capacity to selectively absorb CO 2 . [7][8][9] However, in essence the use of MOF adsorbents relies on pressure, temperature, and/or vacuum swings, thus implying that the release process of adsorbed CO 2 mainly depends on vacuum or heating operations, which are very energy-consuming. The search for new stimuli with a lower or even zero energy cost for triggering CO 2 release is therefore an urgent task and a big challenge. In this regard, light, and especially sunlight, is the best choice.Recent advances reveal that the incorporation of lightsensitive azobenzene units into the metal-organic framework could enable this goal to be reached. [10][11][12] The choice of the azobenzene unit lies in the fact that under UV irradiation it can undergo reversible trans-to-cis isomerization with a distance change between the para carbon atoms from 9 to 5.5 . The structural change greatly facilitates CO 2 release. In a recent finding by Hill and co-workers, up to 64 % desorption capacity was observed. [12] For true low-energy CO 2 capture and release, the development of new MOF materials with similar responses in the visible region is imperative.Taking these points into account, we have developed a distinct strategy in this respect. A diarylethene derivative (L; Scheme 1) with two N-donor sites was used to construct a diarylethene MOF (DMOF). The photoresponsive diarylethene unit undergoes an exquisite change triggered by UV and visible light between open-ring and closed-ring isomers, and the large skeletal structure provides a cha...

In this communication, a novel photochromic molecular switch DTE-2(Azo-CN) containing both dithienylethene and push-pull azo chromophores was synthesized. The push-pull azo chromophores can significantly accelerate the ring opening of the C-C bond of DTE closed isomer when irradiated with light far away from the maximum absorption band of the DTE closed isomer.