Alternations of crystalline and amorphous states largely influence the solid‐state properties of molecular materials. In their Research Article (e202217054), Dongpeng Yan and co‐workers show that the ...transformation between two states of an anthracene‐based metal‐organic complex can tune the photosalient effect, mechanical luminescence, and photochromism behavior. The effect was assigned to competitive chemical routes between a photocycloaddition reaction in the crystalline state and photogenerated radicals in the amorphous state.
Uncovering differences between crystalline and amorphous states in molecular solids would both promote the understanding of their structure–property relationships, as well as inform development of ...multi‐functional materials based on the same compound. Herein, for the first time, we report an approach to leverage crystalline and amorphous states of a zero‐dimensional metal‐organic complex, which exhibited negative and positive photochromism, due to the competitive chemical routes between photocycloaddition and photogenerated radicals. Furthermore, different polymorphs lead to the on/off toggling of photo‐burst movement (photosalient effect), indicating the controllable light‐mechanical conversion. Three demos were further constructed to support their application in information encryption and anti‐counterfeiting. This work provides the proof‐of‐concept of a state‐ and polymorph‐dependent photochemical route, paving an effective way for the design of new dynamically responsive systems.
An approach to leverage crystalline and amorphous states of a zero‐dimensional metal‐organic complex in order to tune negative and positive photochromism was proposed, which could be assigned to the competitive chemical routes between photocycloaddition and photogenerated radicals. Furthermore, both polymorphs exhibit mechanochromic photoemission, and lead to the on/off toggling of the light‐driven motion of bulky molecular crystals.
Conventional polyurethane fiber (CPUF) has been widely used in clothes, but it is difficult to color CPUF into a deep hue with acid dyes. In this work, it is proposed that polyurethane is synthesized ...using dicyclohexylmethane-4,4′-diisocyanate (HMDI) and N-tert-butyldiethanolamine (TBDEA), named poly(HMDI-TBDEA), and is added to a CPUF spinning solution to prepare a modified polyurethane fiber (MPUF) which has an enhanced dyeability toward acid dyes. It is assumed that poly(HMDI-TBDEA) brings tertiary amine groups and tert-butyl groups to MPUF, of which the tertiary amine groups can be protonated under acidic conditions and electrostatically adsorbs anionic ions of acid dyes, and the tert-butyl groups disrupt the ordered arrangement of hard segments in polyurethane to increase the accessible area for acid dyes. The synthesis of poly(HMDI-TBDEA) was validated by proton and carbon nuclear magnetic resonance spectroscopy (1H and 13C NMR) and gel permeation chromatography. MPUF was characterized by differential scanning calorimetry, thermogravimetry, X-ray diffraction, and the tensile test. The study revealed that the addition of poly(HMDI-TBDEA) disrupted the ordered arrangement of the hard segments and strengthened the soft segments but had no obvious influence on the thermal stability. In comparison with CPUF, MPUF exhibited approximately the same elastic recovery, despite a drop in the elongation at break and the break strength. The zeta potential test demonstrated that MPUF might be protonated for enhanced electropositivity under acidic conditions. MPUF displayed superior dyeability than CPUF when dyed with C.I. Acid Orange 7 at pH 3.
A serpin was identified in normal mammary gland by differential cDNA sequencing. In situ hybridization has detected this serpin exclusively in the myoepithelial cells on the normal and noninvasive ...mammary epithelial side of the basement membrane and thus was named myoepithelium-derived serine proteinase inhibitor (MEPI). No MEPI expression was detected in the malignant breast carcinomas. MEPI encodes a 405-aa precursor, including an 18-residue secretion signal with a calculated molecular mass of 46 kDa. The predicted sequence of the new protein shares 33% sequence identity and 58% sequence similarity to plasminogen activator inhibitor (PAI)-1 and PAI-2. To determine whether MEPI can modulate the in vivo growth and progression of human breast cancers, we transfected a full-length MEPI cDNA into human breast cancer cells and studied the orthotopic growth of MEPI-transfected vs. control clones in the mammary fat pad of athymic nude mice. Overexpression of MEPI inhibited the invasion of the cells in the in vitro invasion assay. When injected orthotopically into nude mice, the primary tumor volumes, axillary lymph node metastasis, and lung metastasis were significantly inhibited in MEPI-transfected clones as compared with controls. The expression of MEPI in myoepithelial cells may prevent breast cancer malignant progression leading to metastasis.
Photo‐controllable persistent luminescence at the single crystal level can be achieved by the integration of long‐lived room temperature phosphorescence (RTP) and photochromism within metal–organic ...frameworks (MOFs) for the first time. Moreover, the multiblock core–shell heterojunctions have been prepared utilizing the isostructural MOFs through an epitaxial growth process, in which the shell exhibits bright yellow afterglow emission that gradually disappears upon further irradiation, but the core does not show such property. Benefitting from combined persistent luminescence and photochromic behavior, a multiple encryption demo can be facilely designed based on the dynamic manipulating RTP via reversible photochromism. This work not only develops new types of dynamically photo‐controllable afterglow switch, but also provides a method to obtain MOFs‐based optical heterojunctions towards potential space/time‐resolved information encryption and anti‐counterfeiting applications.
Multiblock core–shell MOFs heterojunctions were prepared through an epitaxial growth process, in which the shell exhibits both persistent luminescence and photochromic properties. The bright yellow afterglow in MOFs shell can be detected before irradiation but almost disappears after coloration upon continuous UV irradiation.
InGaN based light-emitting diodes (LEDs) with undoped GaN interlayer of variant thicknesses grown by metal-organic chemical vapor deposition technique have been investigated. It was found that the ...thickness of undoped GaN interlayers affected LEDs' performance greatly. The LED with 50 nm undoped GaN interlayer showed higher light output power and lower reverse-leakage current compared with the others at 20 mA. Based on electrical and optical characteristics analysis and numerical simulation, these improvements are mainly attributed to the improvement of the quality of depletion region by inserting an undoped GaN layer, as well as reduction of the Shockley-Read-Hall recombination in InGaN/GaN MQWs.
PDF
