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A series of dodecanuclear highly positively charged homo- and heterometallamacrocycles [{Pd(η 3 -2-Me-C 3 H 4 )} 6 (4-PPh 2 py) 12 {M 2 (tpbz)} 3 ] 18+ (M=Pd, Pt; tpbz=1,2,4,5-tetrakis(diphenylphosphanyl)benzene were synthesized by the quantitative self-assembly of {Pd(η 3 -2-Me-C 3 H 4 )} + , {M 2 (tpbz)} 4+ and 4-PPh 2 py moieties in 2:1:4 molar ratio. The cationic assemblies were obtained as salts of different fluorinated anions with diverse sizes and electronic properties, namely BF 4 - , PF 6 - , SbF 6 - and CF 3 SO 3 - . The new crown-like metallamacrocycles showed remarkable differences in their NMR spectra due to the presence of the different counteranions. On the basis of the observed variations, the metallacycles have been tested as catalytic precursors in allylic alkylation reactions. The anion-dependent activity and selectivity has been analysed and compared with that of the corresponding monometallic allylic corners [Pd(η 3 -2-Me-C 3 H 4 )(4-PPh 2 py) 2 ]X (X=BF 4 - , PF 6 - , SbF 6 - , CF 3 SO 3 - ). DFT calculations have been employed in order to help to the interpretation of the experimental data and to model the anion-crown interactions., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The gas-phase fragmentation behavior of self-assembled metallo-supramolecular rhombs based on an unusual chiral [2.2]paracyclophane bis(pyridine) ligand is studied by collision-induced dissociation mass spectrometry. The fragmentation patterns strongly depend on the charge state of the respective mass-selected aggregate. For the doubly charged ions, simple symmetric fragmentation is observed in full accordance with previous results reported for related metallo-supramolecular species. The triply charged species cleaves unsymmetrically which can be rationalized by a preferred formation of ions with low charge density. CID of the quadruply charged rhomb reveals a complex fragmentation. Besides ligand oxidation to the radical cation, facile cleavage of the central covalently bound part of the [2.2]paracyclophane ligand takes place which is even preferred over rupture of the weak dative pyridine-Pd bond.

A series of selectively self-assembled metallo-supramolecular square-like macrocycles with unsymmetric ditopic linkers and two different types of metal corners, i.e., {Pd(η 3 -2-Me-C 3 H 4 )} and {M(dppp)} with dppp = 1,3-bis(diphenylphosphino)propane and M = Pd 2+ or Pt 2+ , have been studied in the gas phase using collision-induced dissociation. The aggregates show distinct fragmentation patterns determined by ligand length, i.e, aggregate size, and type of metal corner. Information on relative binding strength can be deduced. This is of particular interest for (methylallyl)Pd as a relatively new building block in metallo-supramolecular chemistry. The phosphane end of the unsymmetric ligand connected to (η 3 -2-Me-C 3 H 4 )Pd is bound significantly stronger than its pyridine end to (dppp)Pt and (dppp)Pd. These results are corroborated by DFT calculations.

By employing the subcomponent self-assembly approach utilizing 5,10,15,20-tetrakis(4-aminophenyl)porphyrin or its zinc(II) complex, 1H-4-imidazolecarbaldehyde, and either zinc(II) or iron(II) salts, we were able to prepare O-symmetric cages having a confined volume of ca. 1300 Å 3 . The use of iron(II) salts yielded coordination cages in the high-spin state at room temperature, manifesting spin-crossover in solution at low temperatures, whereas corresponding zinc(II) salts led to the corresponding diamagnetic analogues. The new cages were characterized by synchrotron X-ray crystallography, high-resolution mass spectrometry, and NMR, Mössbauer, IR, and UV/Vis spectroscopy. The cage structures and UV/Vis spectra were independently confirmed by state-of-the-art DFT calculations. A remarkably high-spin-stabilizing effect through encapsulation of C 70 was observed. The spin-transition temperature T 1/2 is lowered by 20 K in the host-guest complex., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The square-like homo- and heterometallamacrocycles [{Pd(η(3) -2-Me-C3 H4 )(L(n) )2 }2 {M(dppp)}2 ](CF3 SO3 )6 (dppp=1,3-bis(diphenylphosphino)propane) and [{Pd(η(3) -2-Me-C3 H4 )(L(1) )2 }2 {M(PPh3 )2 }2 ](CF3 SO3 )6 [py=pyridine, M=Pd, Pt, L(n=) 4-PPh2 py (L(1) ), 4-C6 F4 PPh2 py (L(2) )] containing allyl corners were synthesised by antisymbiotic self-assembly of the different palladium and platinum metallic corners and the ambidentate N,P ligands. All the synthesised assemblies displayed a complex dynamic behaviour in solution, the rate of which is found to be dependent on the electronic and/or steric nature of the different building blocks. A kinetico-mechanistic study by NMR line shape analysis of the dynamics of some of these assemblies was undertaken in order to determine the corresponding thermal activation parameters. Both an enhanced thermodynamic stability and slower dynamics were observed for platinum-pyridine-containing species when compared with their palladium analogues. Time-dependent NMR spectroscopy in combination with ESI mass spectrometry was used to study the exchange between the assemblies and their building blocks, as well as that occurring between different metallamacrocycles. Preliminary studies were carried out on the activity of some of the metallamacrocyclic compounds as catalytic precursors in the allylic substitution reaction, and the results compared with that of the monometallic allylic corner [Pd(η(3) -2-Me-C3 H4 )(L(1) )2 ](+) ., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A simple approach toward preparation of heteroleptic two-dimensional (2D) rectangles and three-dimensional (3D) triangular prisms is described utilizing the HETPYP (HETeroleptic PYridyl and Phenanthroline metal complexes) concept. By mixing metal-loaded linear bisphenanthrolines of varying lengths with diverse (multi)pyridine (py) ligands in a proper ratio, six different self-assembled architectures arise cleanly and spontaneously in the absence of any template. They are characterized by (1)H and DOSY NMR, ESI-FT-ICR mass spectrometry as well as by Job plots and UV-vis titrations. Density functional theory (DFT) computations provide information about each structure. A stoichiometry-controlled supramolecule-to-supramolecule interconversion based on the relative amounts of metal bisphenanthroline and bipyridine forces the rectangular assembly to reorganize to a rack architecture and back to the rectangle, as clearly supported by variable temperature and DOSY NMR as well as dynamic light scattering data. The highly dynamic nature of the assemblies represents a promising starting point for constitutional dynamic materials.

A stoichiometric variant of the HETPYP concept (HETeroleptic PYridine and Phenanthroline metal complexes) opens the venue to heteroleptic metallosupramolecular HETPYP-I assemblies both in solution and the solid state, involving the trigonal [Cu(phenAr(2))(py)](+) coordination motif (phenAr(2) = 2,9-diarylphenanthroline; py = various oligopyridines). Combining the same building blocks at another stoichiometric ratio furnished metallosupramolecular HETPYP-II aggregates in the solid state, now based on the tetrahedral [Cu(phenAr(2))(py)(2)](+) coordination motif. Thus, a stoichiometry-controlled structural changeover based on the relative amounts of oligopyridines leads from a discrete assembly with trigonally coordinated copper(I) centers to a coordination polymer with tetrahedrally coordinated copper(I) ions, as shown by solid state studies. In solution, the analysis of both stoichiometric variants indicates that the HETPYP-I structure is congruent with that in the solid state, while the HETPYP-II assembly, as established through DOSY NMR and dynamic light scattering measurements, is only oligomeric at low temperature. At room temperature, i.e. due to entropic costs, the latter assembly prefers to keep "unsaturated" coordination sites that are in rapid exchange, making it an interesting system as a dynamic protecting group and for constitutional dynamic materials through the exchange and reshuffling of components.

Plant genetic engineering has the potential to introduce new allergenic proteins into foods but, at the same time, it can be used to remove established allergens. Here, we report the molecular characterization of Lyc e 3, a new tomato (Lycopersicon esculentum) allergen, and the efficient down-regulation of its expression in transgenic tomato plants. Following the identification of an immunoglobulin E (IgE)-binding 9-kDa polypeptide in tomato peel, designated Lyc e 3, its partial amino acid sequence was determined by N-terminal protein sequencing. Sequence comparison revealed that Lyc e 3 encodes a nonspecific lipid transfer protein (ns-LTP). In plants, ns-LTPs are encoded by large gene families which differ in primary amino acid sequence, expression and proposed cellular function. To identify Lyc e 3 encoding complementary DNAs (cDNAs), public tomato expressed sequence tag (EST) databases were screened for ns-LTP sequences. Following this strategy, two cDNAs, LTPG1 and LTPG2, with high homology to the N-terminal sequence of Lyc e 3, were identified. Ectopic expression of LTPG1 and LTPG2 in Escherichia coli, followed by immunoblotting, verified their IgE reactivity. Subsequently, transgenic tomato plants constitutively expressing LTPG1- or LTPG2-specific double-stranded RNA interference (dsRNAi) constructs were created and tested for the suppression of Lyc e 3 accumulation. Efficient silencing of Lyc e 3 was documented by Northern and Western blotting. In both cases, Lyc e 3 accumulation was decreased to levels below the detection limit (less than 0.5% of the wild-type protein). The allergenic potential of Lyc e 3-deficient tomato fruits was tested by measuring histamine release from sensitized human basophils stimulated with transgenic and parental lines. These assays revealed a strong (10- to 100-fold) decrease in histamine release of human basophils challenged with transgenic fruit extracts when compared with control extracts. These results demonstrate the feasibility of creating low allergenic tomato fruits by means of dsRNAi inhibition.