Bootstrapping Probabilistic Models of Qualitative Spatial Relations for Active Visual Object Search

In many real world applications, autonomous mobile robots are required to observe or retrieve objects in their environment, despite not having accurate estimates of the objects ’ locations. Finding objects in real-world settings is a non-trivial task, given the complexity and the dynamics of human environments. However, by understanding and exploiting the structure of such environments, e.g. where objects are commonly placed as part of everyday activities, robots can perform search tasks more efficiently and effectively than without such knowledge. In this paper we investigate how probabilistic models of qualitative spatial relations can improve the performance in object search tasks. Specifically, we learn Gaussian Mixture Models of spatial relations between object classes from descriptive statistics of real office environments. Experimental results with a range of sensor models suggest that our model improves overall performance in object search tasks.

Labeling the ER for Light and Fluorescence Microscopy

The ER is a highly dynamic network of tubules and membrane sheets. Hence imaging this organelle in its native and mobile state is of great importance. Here we describe methods of labeling the native ER using fluorescent proteins and lipid dyes as well as methods for immunolabeling on plant tissue

The 4-pyridonyl group as a multifunctional electron donor in 1,8-naphthalimide-based photoluminescent and mechanically interlocked coordination compounds

A new ligand system incorporating the 4-pyridonyl group as a substituent in 1,8-naphthalimide compounds is presented, with the pyridone group acting as both an electron donor for the internal charge transfer (ICT) fluoresence process and as a metal binding moiety. After establishing the solution-state photophysical properties of the new pyridyl and carboxyphenyl derivatives L1 and HL2, respectively, we have prepared and characterised four crystalline d¬-block metal complexes containing the 4-(4-pyridonyl)-1,8-naphthalimide residue. Complex 1, a discrete mononuclear Ag(I) complex, and complexes 2 and 3, both one-dimensional Zn(II) coordination polymers, all exhibit striking photoluminescence in the crystalline phase, the nature of which can be related to the solid-state behaviour of the pyridone substituent. Complex 4, a permanently porous Cu(II) material, shows no photoluminesence, but instead reveals a rare and intriguing inclined 2D?3D polyrotaxane architecture, an unusual class of mechanically interlocked network in which the particular coordination chemistry of the pyridone group facilitates alternating looped and linear structural features

Anisotropic Thermal and Guest-Induced Responses of an Ultramicroporous Framework with Rigid Linkers

The interdependent effects of temperature and guest uptake on the structure of the ultramicroporous metal-organic framework [Cu3 (cdm)4 ] (cdm=C(CN)2 (CONH2 )- ) were explored in detail by using in situ neutron scattering and density functional theory calculations. The tetragonal lattice displays an anisotropic thermal response related to a hinged "lattice-fence" mechanism, unusual for this topology, which is facilitated by pivoting of the rigid cdm anion about the Cu nodes. Calculated pore-size metrics clearly illustrate the potential for temperature-mediated adsorption in ultramicroporous frameworks due to thermal fluctuations of the pore diameter near the value of the target guest kinetic diameter, though in [Cu3 (cdm)4 ] this is counteracted by a competing contraction of the pore with increasing temperature as a result of the anisotropic lattice response

Fused aza-heterocyclic ligands: expanding the MOF chemist's toolbox

Azolate-containing ligands have played an important role in the development of water-stable metal-organic frameworks (MOFs) and related materials due to their particularly strong bonding with earth-abundant first row transition metal ions. Fused ring analogues of pyrazole, imidazole and triazole offer untapped potential to expand the scope of these systems as compact, robust anionic bridging ligands with much greater control over bridging geometries, pendant functionalities and electronic properties. The current design approaches in these systems have been directed by two separate methodologies. In one direction, the simple azoles imidazole, pyrazole and 1,2,4-triazole have been built up by adding fused ring functionality to increase complexity and allow new linker geometries. Meanwhile, in the search for biologically-compatible MOFs, purines such as adenine and hypoxanthine have been explored as linkers and their backbone functionalities optimised to prioritise stability and bridging geometry, leading independently to MOF linkers with similar key features. This highlight article surveys the convergence of these two approaches which both point to the benefits of fused 5-6 ring systems for their electronic and structural properties, and considers the key features that the ideal compact and stable heterocyclic linkers in functional metal-organic frameworks might contain

Tetraarylpyrrolo[3,2-b]pyrroles as versatile and responsive fluorescent linkers in Metal-Organic Frameworks

The first examples of crystalline coordination polymers containing the tetraarylpyrrolo[3,2-b]pyrrole (TPP) fluorophore are presented. We have prepared three new TPP ligands L1, H2L2 and H2L3, containing nitrile, carboxylate and mixed imidazole-carboxylate donor functionality, respectively. The ligands themselves each show significant fluorescence in the solution phase, with the nitrile species exhibiting solvatofluorochromism and the two carboxylate-containing compounds exhibiting concentration-dependent emission colour suggesting aggregation processes in solution. Three 3-dimensional polymeric structures are then presented. The compound poly-[AgL12]SbF6·3THF·2H2O 1 is an eightfold-interpenetrated diamondoid material, while poly-[Zn4O(L2)3]·20DMA·10H2O 2 is a porous Metal-Organic Framework with pcu topology, and both 1 and 2 show notable luminescence in the solid state. Complex 2 readily undergoes guest exchange accompanied by a reversible switching in emission colour with no change in chemical structure. While complex poly-[CdL3]·2.5DMA·3.5H2O 3 is non-emissive, it displays a twofold interpenetrated pts topology with hexagonal symmetry and an extremely long hexagonal pitch of 100.3 Å, and shows an impressive 22 wt% CO2 uptake capacity at 278 K and 1 bar

Crystallographic studies of 2-picolyl substituted naphthalene diimide and bis-phthalimide ligands and their supramolecular coordination chemistry

Here we report the synthesis of two N-(2-picolyl) substituted bis-imide ligands, N,N'-di(2-picolyl)-1,4,5,8-naphthalenetetracarboxylic diimide L1 and N,N'-di(2-picolyl)-4,4'-oxybisphthalimide L2, and describe their coordination chemistry in the crystalline state with late d-block metals, with the intention of probing the applicability of the recently reported N,O-chelating mode observed in N-(2-picolyl) substituted 1,8-naphthalimides. Four new crystalline coordination compounds have been prepared and structurally characterised; poly-[Zn(L1)Cl2]·3(C3H6O) 1 and poly-[ZnCl2(L1)]·MeCN 2 are structurally related one-dimensional coordination polymers whose extended structure contains well-defined solvent channels, the nature of which is coupled to the ability of the lattice solvent molecules to undergo n?p interactions with the 1,4,5,8-napthaletetracarboxylic diimide (NDI) core. [H2L1][ZnCl4]·2H2O 3 is a hydrogen-bonded structure of tetrachlorozincate anions bound by the doubly protonated H2L1 cation, while repeating this reaction in the presence of copper(II) ions gave the ligand dihydrochloride salt (H2L1)2Cl 4. Finally, reaction of L1 with AgSbF6 gave the one-dimensional polymer poly-[AgL1]SbF65, in which weak but notable carbonyl coordination was observed in addition to stronger coordination from the pyridyl groups. Conversely, compound L2 failed to convincingly show any reaction or coordination with transition metals, and only the crystalline ligand itself could be isolated. Analysis of these results, as well as studies into the solution state coordination chemistry of these compounds, suggests an underlying barrier to coordination in these species compared to the 1,8-naphthalimides, but provides interesting avenues for crystal engineering

Coordination chemistry of flexible benzene-1,3,5-tricarboxamide derived carboxylates; notable structural resilience and vaguely familiar packing motifs

Flexible benzene-1,3,5-tricarboxamides (BTAs), organic species well-known for their tendencies to form functional soft-materials by virtue of their complementary hydrogen bonding, are explored as structurally reinforcing supramolecular building blocks in porous coordination polymers. We report the synthesis and characterisation of two related, carboxylate-terminated BTA derivatives, and the structure and functionality of their polymeric Cd(II) complexes. The polycarboxylate ligand benzene-1,3,5-tricarboxamide tris(phenylacetic acid) H3L1 was prepared, and the analogous trimethyl benzene-1,3,5-tricarboxamide tris acetate Me3L2 was prepared and its single crystal structure elucidated. On reaction with cadmium nitrate in a DMF/H2O mixture, each BTA compound yielded coordination polymer species with columnar packing motifs comparable to the familiar BTA triple helix seen in purely organic systems. In the case of Me3L2, this transformation was achieved through a convenient in situ ester hydrolysis. Complex 1 is a 2-dimensional layered material containing tubular intralayer pores, in which amide–amide hydrogen bonding is a notable structural feature. In contrast, the structure of 2 contains no amide–amide hydrogen bonding, and instead a columnar arrangement of ligand species is linked by trinuclear Cd(II) cluster nodes into a densely packed three-dimensional framework. The crystal structures revealed both materials exhibited significant solvent-accessible volume, and this was probed with thermal analysis and CO2 and N2 adsorption experiments; complex 2 showed negligible gas uptake, while compound 1 possesses an unusually high CO2 capacity for a two-dimensional material with intralayer porosity and surprising structural resilience to guest exchange, evacuation and exposure to air

Supramolecular aggregation properties of 4-(N-morpholino)-1,8-naphthalimide based fluorescent materials

Here we report the synthesis of two morpholino-substituted naphthalimide ligands, N-(3-picolyl)-4-(N-morpholino)-1,8-naphthalimide L1 and N-benzyl-4-(N-morpholino)-1,8-naphthalimide L2, and study their supramolecular properties in the crystalline, solution and gel phases. These ligands were designed through incorporation of the morpholino group to enhance their photophysical and pH-responsive properties following recently reported N-(3-picolyl) naphthalimide metallogels. L1 was found to form metallogels on reaction with either Mn2+ or Co2+. The gels were found to be thermally and chemically responsive to various stimuli including pH. Conversely, L2 showed no reaction or coordination with transition metals, and did not gel under analogous conditions to L1 . In the solution state, the fluorescence of both L1 and L2 exhibited pH responsiveness and counterion-influenced aggregation. The microparticle formation over the pH range was further investigated through Dynamic Light Scattering and Scanning Electron Microscopy. These two ligands illustrate how a modular ligand family can derive structure-function relationships and allow for systematic tuning, thus allowing for the future development of luminescent pH responsive soft materials

Flexible Porous Coordination Polymers from Divergent Photoluminescent 4-Oxo-1,8-naphthalimide Ligands

Two new luminescent ditopic naphthalimide-derived ligands, N-(4-cyanophenylmethylene)-4-(4-cyanophenoxy)-1,8-naphthalimide (L3) and N-(4-carboxyphenylmethylene)-4-(4-carboxyphenoxy)-1,8-naphthalimide (H2L4), have been prepared, and their coordination chemistry has been explored in the synthesis of three new coordination polymer materials. Complex poly-[Ag(L3)2]BF4·4.5H2O·0.5THF (1) is a 3-fold 2D ? 2D parallel interpenetrated coordination polymer in which three interwoven sheets define inter- and intralayer channels containing anions and solvent molecules. Molecules of L3 interact in 1 through dominant head-to-head p-p stacking interactions, in an opposite aggregation mode to that observed in the free ligand in the crystalline phase. Complexes poly-[Cu(L4)(OH2)]·2DMF·0.5H2O (2) and poly-[Cd2(L4)2(OH2)2]·1.5DMF·3H2O (3) are related oninterpenetrated two-dimensional coordination polymers defined by one-dimensional metal-carboxylate chains, forming layers that interdigitate with adjacent networks through naphthalimide p-p interactions. Both materials undergo structural rearrangements on solvent exchange with acetonitrile; in the case of 3, this transformation can be followed by single-crystal X-ray diffraction, revealing the structure of the acetonitrile solvate poly-[Cd2(OH2)2(L4)2]·2MeCN (4), which shows a significant compression of the primary channels to accommodate the solvent guest molecules. Both materials display modest CO2 adsorption after complete evacuation, and the original expanded phases can be regenerated by reimmersion in DMF. The photophysical properties of each ligand and complex were also explored, which revealed variations in emission wavelength, based on solid-state interactions, including a notable shift in the fluorescence emission band of 3 upon structural rearrangement to 4