Macrophage type-I and type-II class-A scavenger receptors (MSR-A) are implicated in the pathological deposition of cholesterol during atherogenesis as a result of receptor-mediated uptake of modified low-density lipoproteins (mLDL). MSR-A can bind an extraordinarily wide range of ligands, including bacterial pathogens, and also mediates cation-independent macrophage adhesion in vitro. Here we show that targeted disruption of the MSR-A gene in mice results in a reduction in the size of atherosclerotic lesions in an animal deficient in apolipoprotein E. Macrophages from MSR-A-deficient mice show a marked decrease in mLDL uptake in vitro, whereas mLDL clearance from plasma occurs at a normal rate, indicating that there may be alternative mechanisms for removing mLDL from the circulation. In addition, MSR-A-knockout mice show an increased susceptibility to infection with Listeria monocytogenes or herpes simplex virus type-1, indicating that MSR-A may play a part in host defence against pathogens.

Chemosensors detect a single target molecule from among several molecules, but cannot differentiate targets from one another. In this study, we report a molecular decoding strategy in which a single host domain accommodates a class of molecules and distinguishes between them with a corresponding readout. We synthesized the decoding host by embedding naphthalenediimide into the scaffold of an entangled porous framework that exhibited structural dynamics due to the dislocation of two chemically non-interconnected frameworks. An intense turn-on emission was observed on incorporation of a class of aromatic compounds, and the resulting luminescent colour was dependent on the chemical substituent of the aromatic guest. This unprecedented chemoresponsive, multicolour luminescence originates from an enhanced naphthalenediimide–aromatic guest interaction because of the induced-fit structural transformation of the entangled framework. We demonstrate that the cooperative structural transition in mesoscopic crystal domains results in a nonlinear sensor response to the guest concentration.

Flexible porous coordination polymers change their structure in response to molecular incorporation but recover their original configuration after the guest has been removed. We demonstrated that the crystal downsizing of twofold interpenetrated frameworks of [Cu(2)(dicarboxylate)(2)(amine)](n) regulates the structural flexibility and induces a shape-memory effect in the coordination frameworks. In addition to the two structures that contribute to the sorption process (that is, a nonporous closed phase and a guest-included open phase), we isolated an unusual, metastable open dried phase when downsizing the crystals to the mesoscale, and the closed phase was recovered by thermal treatment. Crystal downsizing suppressed the structural mobility and stabilized the open dried phase. The successful isolation of two interconvertible empty phases, the closed phase and the open dried phase, provided switchable sorption properties with or without gate-opening behavior.

A growing attachment: Porous coordination polymer (PCP) nanorods are synthesized by modulation of the coordination equilibria between framework components, which regulates the rate of framework extension and crystal growth. Investigation of the crystal growth mechanism by TEM indicates that face-selective modulation on the surfaces of PCP crystals enhances the anisotropic crystal growth of nanorods by an oriented attachment mechanism.

A simple and straightforward method combines microwave-assisted solvothermal conditions with the coordination modulation method to achieve the size-controlled formation of the porous coordination polymer (PCP), [Cu 3 (btc) 2 ] (where btc represents benzene-1,3,5-tricarboxylate) in the nano/micro regimes. The addition of a monocarboxylic acid modulator to the reaction mixture greatly influenced the morphology of the resulting sample, through competitive coordination interactions during the crystal formation process. By adjusting the concentration of dodecanoic acid additive, we could subtly control the nucleation rate of a [Cu 3 (btc) 2 ] framework and, thus, the resulting crystal size. Homogeneous nanocrystals of the PCP with sizes ranging from few tenths of nanometers up to few micrometers could be successfully obtained in a controlled manner. X-ray diffractions and gas sorption measurements revealed highly crystalline particles with large pore volumes. Moreover, variations in the sorption profiles could be correlated to the size and morphology of the [Cu 3 (btc) 2 ] samples, presenting affinity for gas condensation at high relative pressures or even hierarchical dual porous structures with mesoporous grain boundaries.

MOF on MOF: Core-shell porous coordination polymer (PCP) crystals are fabricated at the single-crystal level by epitaxial growth in solution. Synchrotron X-ray diffraction measurements unveiled the structural relationship between the shell crystal and the core crystal, where in-plane rotational epitaxial growth compensates the difference in lattice constant.

Well-designed metal-organic hybrid porous materials-socalled porous coordination polymers (PCPs) or metalorganic frameworks (MOFs)-can be made from an assembly of organic linkers with metal ions. [1][2][3][4][5][6] This class of materials was recently recognized as an intriguing class of crystalline nanoporous materials for gas sorption, separation, and catalysis because their framework topologies and pore sizes can be designed for selective guest accommodation, and the functionality of the pore surfaces directly influences the interaction with guest molecules. Miniaturizing the size of PCP crystals to the nanometer scale [7][8][9][10] by functionalizing the crystal interfaces will provide further opportunities to integrate novel functions into the materials without changing the characteristic features of the PCP crystal itself, and will allow the correlation between the porous properties and interfacial structures of nanocrystals to be investigated. Despite the advantages of nanosized PCPs, growth processes that are most important in establishing a universal methodology for the creation of nanosized PCPs are still unclear because there is no suitable defining protocol. [7,[10][11][12][13] Understanding the crystal growth of framework materials, moreover, promises to determine the fundamental requirements of bottom-up selfassembly processes. Herein, we show that a simple but straightforward method using capping reagents that perturb the framework extension of PCPs can be applied to determine their crystal features. We describe the tetragonal framework system of PCP nanorods defined by selectively modulating the coordination interaction in the framework, which enhances the one-dimensional anisotropic fusion of the cubic nanocrystals, indicating an oriented attachment mechanism. [14,15] Moreover, the correlation between the sorption properties and crystallinity of the nanorods shows that the coordination modulation method can produce highly crystalline nanorods with high porosity comparable to that of bulk crystals synthesized by using the conventional solvothermal method.The relatively weak interactions of the coordination bonds dominate the hierarchical self-assembly process involved in constructing the sparse three-dimensional porous frameworks of PCPs with nanometer lattice constants, leading to the formation of crystals. This feature distinguishes this class of molecular-based materials from dense inorganic materials, such as metal [16] and semiconductor crystals, [17] and from conventional porous materials such as zeolites [18,19] and mesoporous silica. [20,21] Controlling the interactions between metal ions and organic linkers, so-called "coordination equilibria", is important when varying the crystal features of PCPs, such as their size, morphology, and crystallinity. Although several approaches have been developed to fabricate PCP nanoparticles, such as reversed micelles [22] and microwave-assisted methods, [23,24] the crystal-growth mechanism has rarely been discussed because it is difficult to control th...

Two porous coordination polymers (PCPs) with different pore surface functionality were integrated into one single crystal by face-selective epitaxial growth, leading to BAB-type block PCP crystals with the core crystal A between the second crystals B.