An emerging NIR super-long persistent phosphor and its applications

Materials with the ability to persistently emit intense near-infrared (NIR) light after ceasing excitation are very useful in many fields. The persistent time is a vital parameter for successful applications. In this study, we developed an emerging NIR super-long persistent luminescent (PersL) material, Cr³⁺-activated magnetoplumbite oxide La(Zn/Mg)(Ga,Al)₁₁O₁₉:Cr³⁺, by doping Yb³⁺ as a new efficient electron trap and incorporating Al³⁺ to engineer the energy band. We show that fine control of the trap depth and density is the key underpinning for PersL enhancement. The title material emits intense PersL in the spectral range of 600–950 nm with a PersL time of more than 1,000 h. Furthermore, after undergoing such long-term decay, the NIR emission can be revived by photo-/thermo-stimulation. We demonstrate its potential uses in bioimaging, multilevel anti-counterfeiting, tracing, and positioning. This study provides insight into how energy band engineering manipulates electronic structures to achieve high-performance PersL. The new NIR persistent phosphor may be soon utilized in related applications.     

Enhancement of Non-Gaussianity and Nonclassicality of Photon-Added Displaced Fock State: A Quantitative Approach

Non-Gaussian and nonclassical states and processes are already found to be important resources for performing various tasks related to quantum gravity and quantum information processing. Considering these facts, a quantitative analysis of the nonclassical and non-Gaussian features is performed here for photon added displaced Fock state, as a test case, using a set of measures, namely entanglement potential, Wigner–Yanese skew information, Wigner logarithmic negativity, and relative entropy of non-Gaussianity. It is observed that Fock parameter always increases the amount of nonclassicality and non-Gaussianity, while photon addition is effective only for small values of the displacement parameter. Further, the nonclassical and non-Gaussian effects decrease initially with an increase in the displacement parameter before increasing for the large displacement to saturate to the corresponding Fock state (equivalently displaced Fock state) value. Finally, dynamics of the Wigner function under the effect of photon loss channel is used to show that only highly efficient detectors are able to detect Wigner negativity.     

Three cocrystals and a cocrystal salt of pyrimidin‐2‐amine and glutaric acid

Four new cocrystals of pyrimidin‐2‐amine and propane‐1,3‐dicarboxylic (glutaric) acid were crystallized from three different solvents (acetonitrile, methanol and a 50:50 wt% mixture of methanol and chloroform) and their crystal structures determined. Two of the cocrystals, namely pyrimidin‐2‐amine–glutaric acid (1/1), C₄H₅N₃·C₆H₈O₄, (I) and (II), are polymorphs. The glutaric acid molecule in (I) has a linear conformation, whereas it is twisted in (II). The pyrimidin‐2‐amine–glutaric acid (2/1) cocrystal, 2C₄H₅N₃·C₆H₈O₄, (III), contains glutaric acid in its linear form. Cocrystal–salt bis(2‐aminopyrimidinium) glutarate–glutaric acid (1/2), 2C₄H₆N₃⁺·C₆H₆O₄²⁻·2C₆H₈O₄, (IV), was crystallized from the same solvent as cocrystal (II), supporting the idea of a cocrystal–salt continuum when both the neutral and ionic forms are present in appreciable concentrations in solution. The diversity of the packing motifs in (I)–(IV) is mainly caused by the conformational flexibility of glutaric acid, while the hydrogen‐bond patterns show certain similarities in all four structures.     

Effect of Bulkiness on Reversible Substitution Reaction at MnII Center with Concomitant Movement of the Lattice DMF: Observation through Single‐Crystal to Single‐Crystal Fashion

The porous coordination polymer ({[Mn(L)H₂O](H₂O)_1.5(dmf)}_n, 1 ) (DMF=N,N‐dimethylformamide) exhibits variety of substitution reactions along with movement of lattice DMF molecule depending upon bulkiness of the external guest molecules. If pyridine or 4‐picoline is used as a guest, both lattice and coordinated solvent molecules are simultaneously substituted (complexes 6 and 7 , respectively). If a bulky guest like aniline is used, a partial substitution at the metal centers and full substitution at the channels takes place (complex 8 ). If the guest is 2‐picoline (by varying the position of bulky methyl group with respect to donor N atom), one Mn^II center is substituted by 2‐picoline, whereas the remaining center is substituted by a DMF molecule that migrates from the channel to the metal center (complex 9 ). Here, the lattice solvent molecules are substituted by 2‐picoline molecules. For the case of other bulky guests like benzonitrile or 2,6‐lutidine, both the metal centers are substituted by two DMF molecules, again migrating from the channel, and the lattice solvent molecules are substituted by these guest molecules (complex 10 and 11 , respectively). A preferential substitution of pyridine over benzonitrile (complex 12 ) at the metal centers is observed only when the molar ratio of PhCN:Py is 95:5 or less. For the case of an aliphatic dimethylaminoacetonitrile guest, the metal centers remain unsubstituted (complex 13 ); rather substitutions of the lattice solvents by the guest molecules take place. All these phenomena are observed through single crystal to single crystal (SC–SC) phenomena.     

Guest⊂Guest⊂Host Multicomponent Molecular Crystals: Entrapment of Guest⊂Guest in Honeycomb Networks Formed by Self‐Assembly of 1,3,5‐Tri(4‐hydroxyaryl)benzenes

Sterically‐engineered rigid trigonal molecular modules based on 1,3,5‐tri(4‐hydroxyphenyl)benzenes H1 and H2 undergo O‐H???O hydrogen‐bonded self‐assembly into eight‐fold catenated hexagonal (6,3) and two‐fold interpenetrated undulated square (4,4) networks, respectively. In the presence of [18]crown‐6 as a guest, the triphenol H1 is found to self‐assemble into a honeycomb network with hexagonal voids created between three triphenol building blocks. The guest [18]crown‐6 molecules are found to be nicely nested in hexagonal enclosures. The empty spaces within the crowns can be further filled with neutral (MeOH/water, MeOH/MeNO₂) or ionic guest species such as KI/KAcAc to furnish novel multicomponent assemblies, that is, guest ? guest ? host, that typify Russian dolls. In contrast, triphenol H2 is found to yield analogous multicomponent molecular crystals in which the guest crown–K⁺ acts as a spacers in the hydrogen‐bonded self‐assembly that leads to distorted chicken wire networks.     

Post‐Synthetic Reversible Incorporation of Organic Linkers into Porous Metal–Organic Frameworks through Single‐Crystal‐to‐Single‐Crystal Transformations and Modification of Gas‐Sorption Properties

The porous metal–organic framework (MOF) {[Zn₂(TCPBDA)(H₂O)₂]?30 DMF?6 H₂O}_n ( SNU‐30 ; DMF=N,N‐dimethylformamide) has been prepared by the solvothermal reaction of N,N,N′,N′‐tetrakis(4‐carboxyphenyl)biphenyl‐4,4′‐diamine (H₄TCPBDA) and Zn(NO₃)₂?6 H₂O in DMF/tBuOH. The post‐synthetic modification of SNU‐30 by the insertion of 3,6‐di(4‐pyridyl)‐1,2,4,5‐tetrazine (bpta) affords single‐crystalline {[Zn₂(TCPBDA)(bpta)]?23 DMF?4 H₂O}_n ( SNU‐31 SC ), in which channels are divided by the bpta linkers. Interestingly, unlike its pristine form, the bridging bpta ligand in the MOF is bent due to steric constraints. SNU‐31 can be also prepared through a one‐pot solvothermal synthesis from Zn^II, TCPBDA^4?, and bpta. The bpta linker can be liberated from this MOF by immersion in N,N‐diethylformamide (DEF) to afford the single‐crystalline SNU‐30 SC , which is structurally similar to SNU‐30 . This phenomenon of reversible insertion and removal of the bridging ligand while preserving the single crystallinity is unprecedented in MOFs. Desolvated solid SNU‐30′ adsorbs N₂, O₂, H₂, CO₂, and CH₄ gases, whereas desolvated SNU‐31′ exhibits selective adsorption of CO₂ over N₂, O₂, H₂, and CH₄, thus demonstrating that the gas adsorption properties of MOF can be modified by post‐synthetic insertion/removal of a bridging ligand.     

Nanogel engineering for new nanobiomaterials: from chaperoning engineering to biomedical applications

Nanosize hydrogels (nanogels) are polymer nanoparticles with three‐dimensional networks, formed by chemical and/or physical cross‐linking of polymer chains. Recently, various nanogels have been designed, with a particular focus on biomedical applications. In this review, we describe recent progress in the synthesis of nanogels and nanogel‐integrated hydrogels (nanogel cross‐linked gels) for drug‐delivery systems (DDS), regenerative medicine, and bioimaging. We also discuss chaperone‐like functions of physical cross‐linking nanogel (chaperoning engineering) and organic‐inorganic hybrid nanogels. © 2010 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Published online in Wiley InterScience ( www.interscience.wiley.com ) DOI 10.1002/tcr.201000008     

Vascularization in Bone Tissue Engineering: Physiology,Current Strategies,Major Hurdles and Future Challenges

The lack of a functional vascular supply has, to a large extent, hampered the whole range of clinical applications of ‘successful’ laboratory‐based bone tissue engineering strategies. To the present, grafts have been dependent on post‐implant vascularization, which jeopardizes graft integration and often leads to its failure. For this reason, the development of strategies that could effectively induce the establishment of a microcirculation in the engineered constructs has become a major goal for the tissue engineering research community. This review addresses the role and importance of the development of a vascular network in bone tissue engineering and provides an overview of the most up to date research efforts to develop such a network.