One‐Pot Synthesis of Contracted and Expanded Porphyrins with meso‐CF3 Groups

Corrole and sapphyrin with the smallest meso‐substituents reported so far were prepared in a one‐pot synthesis that relies on a non‐aldehydic precursor for introducing CF₃ groups. The substantial amounts of products obtained by this facile pathway allowed for the full characterization of 5,10,15‐tris(trifluoromethyl)corrole, the access to a variety of stable chelates thereof and investigations that disclose the unique structural and chemical properties induced by the CF₃ substituents. The novel 5,10,15,20‐tetra(trifluoromethyl)sapphyrin undergoes only single protonation, which according to its crystal structure is stabilized by favorable non‐bonding F/H interaction between the meso‐CF₃ and the inverted pyrrolic NH.     

Noncovalent Functionalization of Single-Walled Carbon Nanotube by Porphyrin: Dispersion of Carbon Nanotubes in Water and Formation of Self-Assembly Donor-Acceptor Nanoensemble

A water-soluble nanoensemble of porphyrin and single-walled carbon nanotubes (SWNTs) was fabricated via electrostatic attraction. The formation of this supramolecular complex was monitored by UV-vis spectra and fluorescence spectra. The donor-acceptor properties of this nanoensemble were characterized by I–V performance of relative photovoltaic device fabricated by layer-by-layer (LBL) technique.     

非水溶性卟啉NTPPH_2和ATPPH_2与环糊精超分子体系的光谱学研究

在中性磷酸盐缓冲溶液中,用紫外-可见分光光度法和荧光光谱法研究了非水溶性卟啉5-(4-硝基苯基)-10,15,20-三苯基卟啉(NTPPH2)和5-(4-氨基苯基)-10,15,20-三苯基卟啉(ATPPH2)与α-CD、β-CD和γ-CD三种环糊精相互作用形成的超分子体系。结果表明,NTPPH2与α-CD、β-CD和γ-CD均形成了1:1的包结物,ATPPH2与β-CD形成1:2的包结物,与α-CD和γ-CD则形成了1:1的包结物。其中α-CD与NTPPH2和ATPPH2的包结常数最大。本文探讨了卟啉环上给电子基团和吸电子基团对包结的影响,为卟啉和环糊精相互作用及超分子体系的机理研究提供了基础。     

Noncovalent Assembly of Picket‐Fence Porphyrins on Nitrogen‐Doped Carbon Nanotubes for Highly Efficient Catalysis and Biosensing

A water‐insoluble picket‐fence porphyrin was first assembled on nitrogen‐doped multiwalled carbon nanotubes (CN_x MWNTs) through Fe? N coordination for highly efficient catalysis and biosensing. Scanning electron micrographs, Raman spectra, X‐ray photoelectron spectra, UV/Vis absorption spectra, and electrochemical impedance spectra were employed to characterize this novel nanocomposite. By using electrochemical methods on the porphyrin at low potential in neutral aqueous solution, the presence of CN_x MWNTs led to the direct formation of a high‐valent iron(IV)–porphyrin unit, which produced excellent catalytic activity toward the oxidation of sulfite ions. By using sulfite ions, a widely used versatile additive and preservative in the food and beverage industries, as a model, a highly sensitive amperometric biosensor was proposed. The biosensor showed a linear range of four orders of magnitude from 8.0×10^?7 to 4.9×10^?3 mol L^?1 and a detection limit of 3.5×10^?7 mol L^?1 due to the highly efficient catalysis of the nanocomposite. The designed platform and method had good analytical performance and could be successfully applied in the determination of sulfite ions in beverages. The direct noncovalent assembly of porphyrin on CN_x MWNTs provided a facile way to design novel biofunctional materials for biosensing and photovoltaic devices.     

Very Facile Polarity Umpolung and Noncovalent Functionalization of Inorganic Nanoparticles: A Tool Kit for Supramolecular Materials Chemistry

The facile assembly of shell‐by‐shell (SbS)‐coated nanoparticles [TiO₂?PAC₁₆]@shell 1 – 7 (PAC₁₆=hexadecylphosphonic acid), which are soluble in water and can be isolated as stable solids, is reported. In these functional architectures, an umpolung of dispersibility (organic apolar versus water) was accomplished by the noncovalent binding of ligands 1 – 7 to titania nanoparticles [TiO₂?PAC₁₆] containing a first covalent coating with PAC₁₆. Ligands 1 – 7 are amphiphilic and form the outer second shell of [TiO₂?PAC₁₆]@shell 1 – 7 . The tailor‐designed dendritic building blocks 3 – 5 contain negative and positive charges in the same molecule, and ligands 6 and 7 contain a perylenetetracarboxylic acid dimide (PDI) core ( 6 / 7 ) as a photoactive reporter component. In the redox and photoactive system [TiO₂?PAC₁₆]@shell 7 , electronic communication between the inorganic core to the PDI ligands was observed.     

Fluorescence Spectroscopy of Porphyrins and Phthalocyanines: Some Insights into Supramolecular Self-Assembly,Microencapsulation, and Imaging Microscopy

The molecular interactions of anionic tetrasulfonate phenyl porphyrin (TPPS) with poly(amido amine) (PAMAM) dendrimers of generation 2.0 and 4.0 (G2 and G4, respectively) forming H- or J-aggregates, as well as with human and bovine serum albumin proteins (HSA and BSA), were reviewed in the context of self-assembly molecular complementarity. The spectroscopic studies were extended to the association of aluminum phthtalocyanine (AlPCS₄) detected with a PAMAM G4 dendrimer with fluorescence studies in both steady state and dynamic state, as well as due to the fluorescence quenching associated to electron-transfer with a distribution of lifetimes. The functionalization of TPPS with peripheral substituents enables the assignment of spontaneous pH-induced aggregates with different and well-defined morphologies. Other work reported in the literature, in particular with soft self-assembly materials, fall in the same area with particular interest for the environment. The microencapsulation of TPPS studies into polyelectrolyte capsules was developed quite recently and aroused much interest, which is well supported and complemented by the extensive data reported on the Imaging Microscopy section of the Luminescence of Porphyrins and Phthalocyanines included in the present review.     

Stepwise Stress-Induced Transformations of Metal-Organic Polyhedral Cluster-Based Assemblies: Where Conformational and Supramolecular Features Meet

Understanding the factors governing the formation of supramolecular structures and phase transitions between various forms of molecular crystals is pivotal for developing dynamic, stimuli-responsive materials and polymorph-controlled syntheses. Here, we investigate the pressure-induced dynamic of both the intrinsic molecular structure and the supramolecular network of a predesigned polyhedral oxo-centered zinc cluster incorporating monoanionic N,N’-diphenylformamidinate and featuring N-bonded phenyl groups in close proximity to the primary coordination sphere. We demonstrate that the model oxo cluster is prone to undergoing pressure-induced conformational transformations of the secondary coordination sphere and simultaneous stepwise (initially every second polyhedral molecule undergoes the conformational transformations) and reversible transitions from an ambient phase α to high-pressure phases β and γ, as single-crystal-to-single-crystal events. The observed phase transitions illustrate the key role of an interplay between the low-energy conformation perturbations and cooperative intra- and intermolecular noncovalent interactions.     

Noncovalent Interactions and Crystal Structure Prediction of Energetic Materials

The crystal and molecular structures, intermolecular interactions, and energy of CL-20, HATO, and FOX-7 were comparatively predicted based on molecular dynamic (MD) simulations. By comparison, the 2D fingerprint plot, Hirshfeld surface, reduced density gradient isosurface, and electrostatic potential surface were studied to detect the intermolecular interactions. Meanwhile, the effects of vacuum and different solvents on the crystal habit of CL-20, HATO, and FOX-7 were studied by AE and MAE model, respectively. The energy calculation was also analysed based on the equilibrium structures of these crystal models by MD simulations. Our results would provide fundamental insights for the crystal engineering of energetic materials.     

Ternary Complexes Stabilized by Chalcogen and Alkaline-Earth Bonds: Crucial Role of Cooperativity and Secondary Noncovalent Interactions

High-level G4 calculations show that the strength of chalcogen interactions is enhanced dramatically if chalcogen compounds simultaneously form alkaline-earth bonds. This phenomenon is studied by exploring binary YX₂⋅⋅⋅N-Base complexes and two types of ternary MCl₂⋅⋅⋅YX₂⋅⋅⋅N-Base, YX₂⋅⋅⋅N-Base⋅⋅⋅MCl₂ complexes, in which YX₂ is a chalcogen compound (Y=S, Se; X=F, Cl), the N-Bases are sp, sp², and sp³ bases (NCH, HN=CH₂, NH₃), and MCl₂ are alkaline-earth BeCl₂ or MgCl₂ derivatives. Starting from the chalcogen-bonded complexes YX₂⋅⋅⋅NH₃ and YX₂⋅⋅⋅HN=CH₂, the binding site of a new incoming alkaline-earth bond is found, surprisingly, to depend on the nature of the halogen atom attached to the chalcogen. For the YF₂ binary complexes the association site is the F atom of the YF₂ subunit, whereas for YCl₂ it is the N atom of the nitrogen base. Regarding YX₂⋅⋅⋅NCH complexes, N is the most favorable site for an alkaline-earth interaction in ternary complexes, regardless of which YX₂ derivative is used. The explanation relies on the interplay of all the noncovalent interactions involved: the strong cooperativity between chalcogen and alkaline-earth bonds, and the appearance of secondary noncovalent interactions in the form of hydrogen bonds.     

Contributions of Various Noncovalent Bonds to the Interaction between an Amide and S‐Containing Molecules

N‐Methylacetamide, a model of the peptide unit in proteins, is allowed to interact with CH₃SH, CH₃SCH₃, and CH₃SSCH₃ as models of S‐containing amino acid residues. All of the minima are located on the ab initio potential energy surface of each heterodimer. Analysis of the forces holding each complex together identifies a variety of different attractive forces, including SH???O, NH???S, CH???O, CH???S, SH???π, and CH???π H‐bonds. Other contributing noncovalent bonds involve charge transfer into σ* and π* antibonds. Whereas some of the H‐bonds are strong enough that they represent the sole attractive force in several dimers, albeit not usually in the global minimum, charge‐transfer‐type noncovalent bonds play only a supporting role. The majority of dimers are bound by a collection of several of these attractive interactions. The SH???O and NH???S H‐bonds are of comparable strength, followed by CH???O and CH???S.     

Cesium Recognition by Supramolecular Assemblies of 2-Benzylphenol and 2-Benzylphenolate

Extraction experiments show that 2-benzylphenol is an efficient and selective extractant for cesium. The structures of cesium and potassium 2-benzylphenolate were determined. Both structures also contain 2-benzylphenol, which ligates the cation, through its phenolic oxygen atom and the benzyl ring. The phenolate oxygen atom does not directly contact the cation in either structure, but is a hydrogen-bond acceptor to the 2-benzylphenol ligands, forming a supramolecular assembly. For comparison to the bound ligands, the structure of 2-benzylphenol was also determined. Molecular mechanics and ab initio molecular orbital theory are used to rationalize several aspects of Cs/Na selectivity.     

Adaptive Correction from Virtually Complex Dynamic Libraries: The Role of Noncovalent Interactions in Structural Selection and Folding

The hierarchical self‐assembling of complex molecular systems is dictated by the chemical and structural information stored in their components. This information can be expressed through an adaptive process that determines the structurally fittest assembly under given environmental conditions. We have set up complex disulfide‐based dynamic covalent libraries of chemically and topologically diverse pseudopeptidic compounds. We show how the reaction evolves from very complex mixtures at short reaction times to the almost exclusive formation of a major compound, through the establishment of intramolecular noncovalent interactions. Our experiments demonstrate that the systems evolve through error‐check and error‐correction processes. The nature of these interactions, the importance of the folding and the effects of the environment are also discussed.     

Dissecting Noncovalent Interactions in Carboxyl-Functionalized Ionic Liquids Exhibiting Double and Single Hydrogens Bonds Between Ions of Like Charge

We show that the carboxyl-functionalized ionic liquid 1-(carboxymethyl)pyridinium bis(trifluoromethylsulfonyl)imide [HOOC-CH₂-py][NTf₂] exhibits three types of hydrogen bonding: the expected single hydrogen bonds between cation and anion, and, surprisingly, single and double hydrogen bonds between the cations, despite the repulsive Coulomb forces between the ions of like charge. Combining X-ray crystallography, differential scanning calorimetry, IR spectroscopy, thermodynamic methods and DFT calculations allows the analysis and characterization of all types of hydrogen bonding present in the solid, liquid and gaseous states of the ionic liquid (IL). We find doubly hydrogen bonded cationic dimers (c⁺=c⁺) in the crystalline phase. With increasing temperature, this binding motif opens in the liquid and is replaced by (c⁺−c⁺−a⁻ species, with a remaining single cationic hydrogen bond and an additional hydrogen bond between cation and anion. We provide clear evidence that the IL evaporates as hydrogen-bonded ion pairs (c⁺−a⁻) into the gas phase. The measured transition enthalpies allow the noncovalent interactions to be dissected and the hydrogen bond strength between ions of like charge to be determined.     

Intramolecular Interactions of a Phenyl/Perfluorophenyl Pair in the Formation of Supramolecular Nanofibers and Hydrogels

A new system for the incorporation of a phenyl/perfluorophenyl pair in the structure of a peptide hydrogelator was developed. The strategy is based on the idea that the integration of an end‐capped perfluorophenyl group and a phenylalanine with a phenyl moiety in the side chain forms an intramolecular phenyl/perfluorophenyl pair, which can be used to promote the formation of the supramolecular nanofibers and hydrogels. This work illustrates the importance of structure‐hydrogelation relationship and provides new insights into the design of self‐assembly nanobiomaterials.     

Conceptual Quantum Chemical Analysis of Bonding and Noncovalent Interactions in the Formation of Frustrated Lewis Pairs

The contributions of covalent and noncovalent interactions to the formation of classical adducts of bulky Lewis acids and bases and frustrated Lewis pairs (FLPs) were scrutinized by using various conceptual quantum chemical techniques. Significantly negative complexation energies were calculated for fourteen investigated Lewis pairs containing bases and acids with substituents of various sizes. A Ziegler–Rauk‐type energy decomposition analysis confirmed that two types of Lewis pairs can be distinguished on the basis of the nature of the primary interactions between reactants; dative‐bond formation and concomitant charge transfer from the Lewis base to the acid is the dominant and most stabilizing factor in the formation of Lewis acid–base adducts, whereas weak interactions are the main thermodynamic driving force (>50 %) for FLPs. Moreover, the ease and extent of structural deformation of the monomers appears to be a key component in the formation of the former type of Lewis pairs. A Natural Orbital for Chemical Valence (NOCV) analysis, which was used to visualize and quantify the charge transfer between the base and the acid, clearly showed the importance and lack of this type of interaction for adducts and FLPs, respectively. The Noncovalent Interaction (NCI) method revealed several kinds of weak interactions between the acid and base components, such as dispersion, π–π stacking, C?H ??? π interaction, weak hydrogen bonding, halogen bonding, and weak acid–base interactions, whereas the Quantum Theory of Atoms in Molecules (QTAIM) provided further conceptual insight into strong acid–base interactions.