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Napthalene diimides (NDIs) are attractive candidates for electrical energy storage owing to the stabilisation of complexes between electrogenerated dianions and cations.

Supramolecular polymorphism in dye aggregates and examples of N,O-bidentate boron difluoride complexes are very uncommon in chemistry. Both rarities have been addressed by synthesising a new N,O-bidentate boron difluoride complex PNIBF2, which shows polymorphic aggregation. Depending upon the nature of the solvent and preparation methods, PNIBF2 produced three different aggregates. In a non-polar environment, the dye produced emissive linear nanoaggregates Agg1. In contrast, in a polar solvent (76 : 24 v/v water-THF mixture), the dye produced two different types of cyclic aggregates, nanoellipsoids Agg2 and nanospheres Agg3. Kinetically controlled Agg2 were produced at room temperature, while Agg3 were generated at elevated temperatures. Supramolecular assemblies Agg2 could be readily converted into Agg3 by heating and subsequent slow cooling. Our results highlight the relevance of peri-naphthoindigo as a new molecular building block for the creation of functional supramolecular systems.

Photoluminescence enhancement for all the members of a self-sorted co-aggregate was observed for the first time by successfully amalgamating AIEE and social self-sorting. Intermolecular H-bonding and π–π stacking were utilised to prepare several co-aggregates of peri-naphthoindigo (PNI) and a 4-amino-1,8-naphthalimide derivative dye, NH2-NMI. In the heteromeric aggregates, photoluminescence intensities were increased by 28% for the imide and more than 400% for PNI. Due to spectral overlap between the emission of the imide and the absorption of PNI, energy transfer took place from the former to the latter. The heteromeric aggregates are dual emissive and the relative intensities of the emissions can easily be tuned by varying the stoichiometry of the dyes.

A facile synthesis of peri-naphthoindigo (PNI) was reported for the first time from simple precursor. Installation of a chromophore at the peri-position of naphthalene is very unique in terms of synthetic challenges and properties. PNI exists in monoenol form, undergoes halochromism in acidic medium, and displays a wide and strong absorption band (e = 33390 M–1cm–1) with maxima at 632 nm (chloroform). The dye undergoes oxidation and reduction at +0.30 and −0.58 V (vs Fc/Fc+), respectively, in chloroform.

Self-assembly of octahedral Fe(II) ions and linear perylene bisimide (PBI) dyes with 2,2'-bipyridine groups covalently attached at the imide positions quantitatively yields an Fe4(PBI)6 tetrahedron by the directional bonding approach. With an edge length of 3.9 nm and estimated internal volume950 Å(3), tetrahedron T is one of the largest M4L6 tetrahedra ever reported. Importantly, many of the desirable photo- and electroactive properties of the PBI ligands are transferred to the nanoscale metallosupramolecule. Tetrahedron T absorbs strongly across the visible spectrum out to 650 nm and exhibits a total of 7 highly reversible electrochemical oxidation and reduction waves spanning a 3.0 V range. This facile cycling of 34 electrons between +18 and -16 charged species is likely enabled due to the porous nature of the tetrahedron that allows the necessary counterions to freely flow in and out of the host. Host-guest encapsulation of C60 by T in acetonitrile was studied by (13)C NMR spectroscopy, UV-vis spectroscopy, and ESI-MS, confirming that the tetrahedron is a suitable host for large, functional guest molecules.

Chemical ingenuity will play a significant role in solving the greatest challenge currently facing society: providing clean and carbon neutral energy for all of humanity. Molecular artificial photosynthesis is an emerging technology based on principles learned from Nature where individual components perform the essential light-harvesting, charge-separation, and water splitting functions to store solar energy in the form of chemical bonds. This tutorial review focuses specifically on the application of metallosupramolecular self-assembly strategies to interface solar fuel catalysts with photosensitizers and construct light-harvesting antennae capable of achieving panchromatic absorption and directional energy concentration.

The objective of this work is to study both the dynamics and mechanisms of guest incorporation into the pores of 2D supramolecular host networks at the liquid-solid interface. This was accomplished by adding molecular guests to prefabricated self-assembled porous monolayers and the simultaneous acquisition of scanning tunneling microscopy (STM) topographs. The incorporation of the same guest molecule (coronene) into two different host networks was compared, where the pores of the networks either featured a perfect geometric match with the guest (for trimesic acid host networks) or were substantially larger than the guest species (for benzenetribenzoic acid host networks). Even the moderate temporal resolution of standard STM experiments in combination with a novel injection system was sufficient to reveal clear differences in the incorporation dynamics in the two different host networks. Further experiments were aimed at identifying a possible solvent influence. The interpretation of the results is aided by molecular mechanics (MM) and molecular dynamics (MD) simulations.

The insertion of sulfur dioxide into the Co−C bond in ArCH2Co(dioxime)2Py forms a mixture of ArCH2SO2Co(dioxime)2Py, ClCo(dioxime)2Py, and a neutral trinuclear complex, [(dpgH)2PyCoIII-μ-SO3]2CoII(MeOH)4. The inserted products 4-CN-C6H4CH2SO2Co(dpgH)2Py and C6H5CH2SO2Co(gH)2Py and the trinuclear complex have been structurally characterized by X-ray for the first time. The insertion of sulfur dioxide into the Co−C bond affects the orientation of the benzyl group.

Using motifs from 3-fold completive self-sorting in an eight-component library, we report on the design and fabrication of a fully dynamic trisheterometallic scalene triangle, a demanding supramolecular structure that complements the so far known triangular structures.

The multicomponent synthesis and solution-state characterization of three supramolecular bis-heterometallic isosceles triangles are elaborated. The triangular assemblies are isosceles both geometrically and chemically; they comprise multiple ligands, metals, and binding motifs. Variation of the length of one side of the triangle by changing the number of phenyl spacers n = 0, 1, and 2 influences the redox potential of the opposing copper(I) center, allowing translation of the nanomechanical changes into electronically readable values.

Phenanthroline-terpyridine hybrid 1 was designed as a chameleon-type ligand to satisfy both HETPHEN and HETTAP coordination modes. In the presence of Cu(+), 1 exclusively self-assembled to triangle T1, whereas Zn(2+) addition produced a 2:1 mixture of triangle T2 and square S2. Interconversion between T1 and (T2 + S2) states was triggered by the addition of Zn(2+) and reversed by selectively removing Zn(2+) with ligand 7.

We present a scanning tunneling microscopy (STM) based study of 1,3,5-tris[4'-carboxy(1,1'-biphenyl-4-yl)]benzene (TCBPB) monolayers at the liquid-solid interface. In analogy to smaller aromatic 3-fold symmetric tricarboxylic acids, this compound was aimed to yield two-dimensional nanoporous networks with large cavities. Depending on the solute concentration, three crystallographically distinct phases with pores of different size and shape were observed on graphite (001) with heptanoic acid as solvent. All three phases have the same dimer motif as basic building block in common. Yet, as opposed to other carboxylic acid assemblies, these dimers are not interconnected by 2-fold O-H...O hydrogen bonds as anticipated, but by two energetically inferior C-H...O hydrogen bonds. Instead of the common head-to-head arrangement, this bonding pattern results in displaced dimers, which allow for higher packing density, and due to their lower symmetry give rise to chiral polymorphs. In accordance with studies of comparable systems, a positive correlation between solute concentration and average surface packing density is identified and rationalized by thermodynamic arguments.

Clean fabrication of a five-component supramolecular triangle was elaborated via self-sorting. The robustness of the dynamic triangle against external stimuli was challenged by varying both the metal ions and their ratios. Self-sorting of five components proved to be superior to that of four components.

Dynamic heteroleptic coordination at metal centres is quite common in Nature and often related to a specific biological function, such as in zinc finger proteins and in hemoglobin for oxygen transport. To achieve the required high heteroleptic fidelity, representative biological systems avail themselves of “intramolecular” multidentate coordination using the protein backbone as a “superligand”. In contrast, dynamic heteroleptic coordination at a single metal centre in solution requires to bind different freely exchanging ligands under thermodynamic control. In this tutorial review we present the emerging principles of how to assemble dissimilar ligands at dynamically exchanging metal centres, with a particular emphasis on using the precepts for the fabrication of heteroleptic supramolecular assemblies in solution.

We present a variable-temperature study of monolayer self-assembly at the liquid-solid interface. By means of in situ scanning tunneling microscopy (STM), reversible phase transitions from a nanoporous low-temperature phase to a more densely packed high-temperature phase are observed. The occurrence of the phase transition and the respective transition temperature were found to depend on the type of solvent and solute concentration. Estimates of the entropic cost and enthalpic gain upon monolayer self-assembly suggest that coadsorption of solvent molecules within the cavities of the nanoporous structure renders this polymorph thermodynamically stable at low temperatures. At elevated temperatures, however, desorption of these relatively weakly bound solvent molecules destabilizes the nanoporous polymorph, and the densely packed polymorph becomes thermodynamically favored. Interestingly, the structural phase transition provides external control over the monolayer morphology and, for the system under discussion, results in an effective opening and closing of supramolecular nanopores in a two-dimensional molecular monolayer.

The amalgamation of two incomplete self-sorting processes into a process that makes quantitative use of all members of the library is described by 2-fold completive self-sorting. Toward this goal, individual metal-ligand binding scenarios were optimized for high thermodynamic stability and best selectivity, by screening a variety of factors, such as steric and electronic effects, pi-pi interactions, and metal-ion specifics. Using optimized, heteroleptic metal-ligand binding motifs, a library of four different ligands (1, 2, 3, 4) and two different metal ions (Zn(2+), Cu(+)) was set up to assess 2-fold completive self-sorting. Out of 20 different combinations, the self-sorting library ended up with only two metal-ligand complexes in basically quantitative yield. To demonstrate the value of 2-fold completive self-sorting for the formation of nanostructures, the optimized, highly selective binding motifs were implemented into three polyfunctional ligands. Their integrative self-sorting in the presence of Zn(2+) and Cu(+) led to the clean formation of the supramolecular trapezoid T, a simple but still unknown supramolecular architecture. The dynamic trapezoid T consists of three different ligands with four different donor-acceptor interactions. Its structure was established by (1)H NMR spectroscopy, electrospray ionization mass spectroscopy, and differential pulse voltammetry (DPV) and by exclusion of alternative structures.

Interfacial self-assembly of specific monolayer structures from solution on a graphite surface can be steered by tuning the interplay between solute–solute and solute–solvent interactions.

The self-assembly of an equilateral triangle that is both heterobimetallic and heteroleptic, its metal exchange to a homometallic triangle and further ligand exchange (= edge of the triangle) were elaborated.