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Organic chromophores have been successfully implemented into supramolecular systems to bestow them with distinct photophysical properties for various applications, ranging from solar energy conversion, photochemical reactions or as receptors for guest molecules with optical readout. We had previously introduced first members of the large family of coal‐tar dyes (methylene blue, crystal violet and rhodamine) as integral components of coordination cages. Here, we add two new chromophores, malachite green (MGP) and a purple phenazinium dye (PHP), serving as backbones of bis‐monodentate banana‐shaped ligands with pyridine donors. We show the formation of corresponding green and purple coloured Pd2L4 coordination cages and investigate their interaction with chiral guest molecules via UV‐Vis and CD spectroscopy. The PHP cage can be used to recognize nucleoside triphosphates, based on chirality transfer from the guests to the structurally flexible helicate. In combination with the already known methylene blue cage MBP we could further differentiate between all four canonical NTPs through characteristic changes in the observed CD signatures. [ABSTRACT FROM AUTHOR]

A strategy to engineer the stacking of diketopyrrolopyrrole (DPP) dyes based on non‐statistical metallosupramolecular self‐assembly is introduced. For this, the DPP backbone is equipped with nitrogen‐based donors that allow for different discrete assemblies to be formed upon the addition of Pd(II), distinguished by the number of π‐stacked chromophores. A Pd3L6 three‐ring, a heteroleptic Pd2L2L′2 ravel composed of two crossing DPPs (flanked by two carbazoles), and two unprecedented self‐penetrated motifs (a Pd2L3 triple and a Pd2L4 quadruple stack), were obtained and systematically investigated. With increasing counts of stacked chromophores, UV/Vis absorptions red‐shift and emission intensities decrease, except for compound Pd2L2L′2, which stands out with an exceptional photoluminescence quantum yield of 51 %. This is extraordinary for open‐shell metal containing assemblies and explainable by an intra‐assembly FRET process. The modular design and synthesis of soluble multi‐chromophore building blocks offers the potential for the preparation of nanodevices and materials with applications in sensing, photo‐redox catalysis and optics. [ABSTRACT FROM AUTHOR]

Es wird eine Strategie zur Stapelung von Diketopyrrolopyrrol‐Farbstoffen (DPP) vorgestellt, die auf einem nicht‐statistischen Ansatz zur metallosupramolekularen Selbstassemblierung beruht. Dazu wird das DPP‐Grundgerüst mit stickstoffbasierten Donoren ausgestattet, die bei Zugabe von Pd(II) Kationen die Bildung verschiedener diskreter Strukturen ermöglichen, welche sich durch die Anzahl der π‐gestapelten Chromophore unterscheiden. Ein Pd3L6‐Dreiring, eine heteroleptische Pd2L2L′2‐Anordnung, bestehend aus zwei sich kreuzenden DPPs (flankiert von zwei Carbazolen), und zwei bisher unbeschriebene, sich selbst durchdringende Motive (ein Pd2L3‐Dreifach‐ und ein Pd2L4‐Vierfachstapel) wurden erhalten und systematisch untersucht. Mit zunehmender Anzahl gestapelter Chromophore kommt es zu einer Rotverschiebung der UV/Vis‐Absorption und einer Abnahme der Emissionsintensität, mit Ausnahme der Verbindung Pd2L2L′2, die eine außergewöhnlich hohe Photolumineszenz‐Quantenausbeute von 51 % aufweist. Dies ist unüblich für Verbindungen, die offenschalige Metallionen enthalten, und lässt sich durch einen intramolekularen FRET‐Prozess erklären. Das modulare Design solcher löslicher Multi‐Chromophor‐Bausteine eröffnet Möglichkeiten für die Herstellung von Nanobauteilen und ‐materialien mit Anwendungen in den Bereichen Sensorik, Photo‐Redox‐Katalyse und Optik. [ABSTRACT FROM AUTHOR]

A strategy to implement four members of the classic coal‐tar dye family, Michler's ketone, methylene blue, rhodamine B, and crystal violet, into [Pd2L4] self‐assemblies is introduced. Chromophores were incorporated into bis‐monodentate ligands using piperazine linkers that allow to retain the auxochromic dialkyl amine functionalities required for intense colors deep in the visible spectrum. Upon palladium coordination, ligands with pyridine donors form lantern‐shaped dinuclear cages while quinoline donors lead to strongly twisted [Pd2L4] helicates in solution. In one case, single crystal X‐ray diffraction revealed rearrangement to a [Pd3L6] ring structure in the solid state. For nine examined derivatives, showing colors from yellow to deep violet, CD spectroscopy discloses different degrees of chiral induction by an enantiomerically pure guest. Ion mobility mass spectrometry allows to distinguish two binding modes. Self‐assemblies based on this new ligand class promise application in chiroptical recognition, photo‐redox catalysis and optical materials. [ABSTRACT FROM AUTHOR]

Wir berichten über den Einbau klassischer Teerfarben (Michlers Keton, Methylen Blau, Rhodamin B und Kristallviolett) in selbstassemblierte Strukturen der Formel [Pd2L4]. Die Chromophore wurden unter Verwendung von Piperazin‐Linkern in bis‐monodentate Liganden integriert. Dies erlaubt die Erhaltung der für die intensive Farbgebung verantwortlichen auxochromen Dialkylamin‐Funktionen. Liganden mit Pyridin‐Donoren bilden laternenförmige dinukleare Käfige, während Chinolin‐Donoren stark gewundene [Pd2L4]‐Helikate ergeben. In einem Fall konnte mittels Röntgenstrukturanalyse eine [Pd3L6]‐Ringstruktur im Festkörper nachgewiesen werden. Für neun untersuchte Derivate, in Farben von Gelb bis Dunkelviolett, konnte mittels CD‐Spektroskopie chirale Induktion durch einen enantiomerenreinen Gast gezeigt werden. Ionenmobilitäts‐Massenspektrometrie erlaubt die Unterscheidung zweier Bindungsmodi. Nanostrukturen basierend auf dieser neuen Ligandenklasse versprechen Anwendungen in chiropitscher Erkennung, Photo‐Redox‐Katalyse und funktionalen Materialien. [ABSTRACT FROM AUTHOR]

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Chemists of all fields currently publish about 50 000 crystal structures per year, the vast majority of which are X‐ray structures. We determined two molecular structures by employing electron rather than X‐ray diffraction. For this purpose, an EIGER hybrid pixel detector was fitted to a transmission electron microscope, yielding an electron diffractometer. The structure of a new methylene blue derivative was determined at 0.9 Å resolution from a crystal smaller than 1×2 μm2. Several thousand active pharmaceutical ingredients (APIs) are only available as submicrocrystalline powders. To illustrate the potential of electron crystallography for the pharmaceutical industry, we also determined the structure of an API from its pill. We demonstrate that electron crystallography complements X‐ray crystallography and is the technique of choice for all unsolved cases in which submicrometer‐sized crystals were the limiting factor. Electrons instead of X‐rays: An electron diffractometer was tailored and employed for de novo structure determination from submicrometer‐sized crystals. A new methylene blue derivative was analysed together with a microcrystalline extract of an active pharmaceutical ingredient from a pill. The results obtained on submicrometer‐sized samples complement X‐ray crystallography. [ABSTRACT FROM AUTHOR]

Abstract: Eine Reihe metallvermittelt gebildeter Käfige mit mehreren Kavitäten wurde unter Verwendung von PdII‐Kationen und drei‐ oder vierzähnigen Liganden synthetisiert und mittels NMR‐Spektroskopie, Massenspektrometrie und Einkristallröntgenstrukturanalyse charakterisiert. Der Erdnuss‐förmige [Pd3L14]‐Käfig auf Basis des dreizähnigen Liganden L1 konnte durch Versetzen mit einem Chlorid‐Salz quantitativ in das interpenetrierte [5Cl@Pd6L18]‐Dimer umgewandelt werden, das eine lineare {[Pd‐Cl‐]5Pd}‐Stapelung und damit ein bisher einzigartiges Strukturmotiv aufweist. Kleinwinkel‐Neutronenstreuexperimente zeigten, dass die Zigarren‐förmigen Gebilde mit einer Länge von 3.7 nm durch solvophobe Wechselwirkungen zwischen den Hexyl‐Seitenketten zu einlagigen Scheiben mit einem Durchmesser von 14 nm aggregieren. Ferner konnte beobachtet werden, dass der hepta‐kationische [5Cl@Pd6L18]‐Käfig mit polyanionischen Oligonukleotid‐Doppelsträngen unter Auflösung der Aggregate in Wasser wechselwirkt, was diese Art von Supramolekülen für Anwendungen interessant macht, die auf nicht‐kovalenter DNA‐Bindung beruhen. [ABSTRACT FROM AUTHOR]

Abstract: A series of metal‐mediated cages, having multiple cavities, was synthesized from PdII cations and tris‐ or tetrakis‐monodentate bridging ligands and characterized by NMR spectroscopy, mass spectrometry, and X‐ray methods. The peanut‐shaped [Pd3L14] cage deriving from the tris‐monodentate ligand L1 could be quantitatively converted into its interpenetrated [5Cl@Pd6L18] dimer featuring a linear {[Pd‐Cl‐]5Pd} stack as an unprecedented structural motif upon addition of chloride anions. Small‐angle neutron scattering (SANS) experiments showed that the cigar‐shaped assembly with a length of 3.7 nm aggregates into mono‐layered discs of 14 nm diameter via solvophobic interactions between the hexyl sidechains. The hepta‐cationic [5Cl@Pd6L18] cage was found to interact with polyanionic oligonucleotide double‐strands under dissolution of the aggregates in water, rendering the compound class interesting for applications based on non‐covalent DNA binding. [ABSTRACT FROM AUTHOR]

Heteroleptic coordination cages, nonstatistically assembled from a set of matching ligands, can be obtained by mixing individual components or via cage-to-cage transformations from homoleptic precursors. Based on the latter approach, we here describe a new level of self-sorting in coordination cage systems, namely, 'heteromeric completive self-sorting'. Here, two heteroleptic assemblies of type Pd 2 A 2 B 2 and Pd 2 A 2 C 2 , sharing one common ligand component A but differing in the other, are shown to coexist in solution. This level of self-sorting can be reached either from a statistical mixture of assemblies based on some ligands B and C or, alternatively, following a first step of integrative self-sorting giving a distinct Pd 2 B 2 C 2 intermediate. While subtle enthalpic factors dictate the outcome of the self-sorting, we found that it is controllable. From a unique set of three ligands, we demonstrate the transition from strict integrative self-sorting forming a Pd 2 AB 2 C cage to heteromeric completive self-sorting to give Pd 2 A 2 B 2 and Pd 2 A 2 C 2 by variation of the ligand ratio. Cage-to-cage transformations were followed by NMR and MS experiments. Single crystal X-ray structures for three new heteroleptic cages were obtained, impressively highlighting the versatility of ligand A to either form a π-stacked trans -figure-of-eight arrangement in Pd 2 A 2 B 2 or occupy two cis -edges in Pd 2 A 2 C 2 or only a single edge in Pd 2 AB 2 C. This study paves the way toward the control of heteroleptic cage populations in a systems chemistry context with emerging features such as chemical information processing, adaptive guest selectivity, or stimuli-responsive catalytic action.

Azulene, a blue structural isomer of naphthalene, is introduced as the backbone for a new family of Pd(II)-based self-assemblies. Three organic ligands, equipped with varying donor groups, produce three [Pd 2 L 4 ] cages of different cavity dimensions. Unexpectedly, the addition of organic disulfonate guests to the smallest lantern-shaped cage (featuring pyridine donors) led to a rapid and quantitative transformation to a distorted-tetrahedral [Pd 4 L 8 ] species. On the contrary, [Pd 2 L 4 ] cages formed from ligands with isoquinoline donors either just encapsulated the guests or showed no interaction. The tetrahedral species could be fully reverted back to its original [Pd 2 L 4 ] topology by capturing the guest by another, stronger binding [Pd 2 L' 4 ] coordination cage, narcissistically self-sorting from the first cage. The azulenes, serving as colored hydrocarbon backbones of minimal atom count, allow one to follow cage assembly and guest-induced transformation by the naked eye. Furthermore, we propose that their peculiar electronic structure influences the system's assembly behavior.

Chemists of all fields currently publish about 50 000 crystal structures per year, the vast majority of which are X-ray structures. We determined two molecular structures by employing electron rather than X-ray diffraction. For this purpose, an EIGER hybrid pixel detector was fitted to a transmission electron microscope, yielding an electron diffractometer. The structure of a new methylene blue derivative was determined at 0.9 Å resolution from a crystal smaller than 1×2 μm 2 . Several thousand active pharmaceutical ingredients (APIs) are only available as submicrocrystalline powders. To illustrate the potential of electron crystallography for the pharmaceutical industry, we also determined the structure of an API from its pill. We demonstrate that electron crystallography complements X-ray crystallography and is the technique of choice for all unsolved cases in which submicrometer-sized crystals were the limiting factor., (© 2018 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.)