Supramolecular Interfacial Assembly: Integrating Supramolecular Hosts into Polymeric Membranes through an Aqueous Interface.

Efficient incorporation of supramolecular hosts in polymeric membranes can impart the overall matrix with new properties for a range of cutting-edge applications. Here, we introduce a Supramolecular Interfacial Assembly (SIA) method for the fabrication of polymeric membranes featuring embedded macrocycles. Through harnessing the quasi-liquid nature of the concentrated polymer solution, SIA orchestrates the homogenous spreading of macrocycles in an aqueous layer on its surface, leading to the creation of an interface between "water/water" phases, subsequently forming a cross-linked membrane driven by supramolecular electrostatic interactions. Remarkably, compared to the traditional interfacial polymerization, SIA adheres to a "green" paradigm without the need for organic solvents. The resultant composite membrane exhibits superior performance in organic solvent nanofiltration (OSN), owing to the precise molecular sieving property provided by the macrocycles with well-defined permanent cavities. This fabrication method holds great promise for the innovative design of composite membranes, which can greatly impact the production of smart membrane materials for advanced technology applications in the future.

Conjugation Paths in Oxatriphyrin(2.1.1) - C2 Bridge Modifications.

An efficiency of delocalization in strongly conjugated systems remains an important factor crucial for modulation of the optical properties directly correlated with its range. An ortho-substituted phenylene derivative bearing electron donating/accepting functionality was built-in a fully unsaturated macrocyclic system with a global delocalization of a diatropic and/or a paratropic current. A precisely located structural modification influence observed behaviour in spectroscopic parameters that are only slightly recognizable in 4n+2 systems but showing a significant influence on the reduced derivatives with a contribution of 4n π-electrons delocalization path.

A Supramolecular Nanoformulation with Adaptive Photothermal/Photodynamic Transformation for Preventing Dental Caries.

In the context of an increasingly escalating antibiotics crisis, phototherapy has emerged as a promising therapeutic approach due to its inherent advantages, including high selectivity, noninvasiveness, and low drug resistance. Photothermal therapy (PTT) and photodynamic therapy (PDT) are two complementary and promising phototherapies albeit with inherent limitations, noted as the challenges in achieving precise heat confinement and the associated risk of off-target damage for PTT, while the constraints due to the hypoxic microenvironment are prevalent in biofilms faced by PDT. Herein, we have designed a supramolecular nanoformulation that leverages the complexation-induced quenching of guanidinium-modified calix[5]arene grafted with fluorocarbon chains (GC5AF5), the efficient recognition of adenosine triphosphate (ATP), and the oxygen-carrying capacity of the fluorocarbon chain. This intelligent nanoformulation enables the adaptive enhancement of both photothermal therapy (PTT) and photodynamic therapy (PDT), allowing for on-demand switching between the two modalities. Our nanoformulation utilizes ATP released by dead bacteria to accelerate the elimination of biofilms, rendering bacteria unable to resist while minimizing harm to healthy tissues. This research highlights the particular recognition and assembly capabilities of macrocycles, offering a promising strategy for creating potent, combined antibiofilm therapies.

Role of Solvent and Noncovalent Interactions in Alkaline Reactivity of Strained and Strain-Free Macrocyclic Disulfides.

This study employs ab initio molecular dynamics simulations to investigate  the impact of solvent and non-bonded interactions on the structure-reactivity relationship of both strain-free and strained macrocyclic disulfides. Our findings reveal that interactions  with water as a solvent significantly influence the minimum energy geometry structures  of both conformers of the studied macrocycle.  In particular, our simulations identify short contacts, specifically S···π-aromatic interactions,  which suppress reactivity for the strained isomer by obstructing the reaction cone at the minimum free energy.   Surprisingly, the free energy barriers for the disulfide reaction with a simple nucleophile (OH- anion) remain very similar,  despite one conformer having a markedly more strained disulfide bond than the other. Enhanced molecular dynamics simulations in explicit solution  elucidate this apparent contradiction by revealing different solvent exposures of the two sulfur atoms in the macrocycles.

A Cycloparaphenylene Acetylene as Potential Precursor for an Armchair Carbon Nanotube.

The bottom-up synthesis of carbon nanotubes (CNTs) is a long-standing goal in synthetic chemists. Producing CNTs with defined lengths and diameters would render these materials and thus their fascinating properties accessible in a controlled way. Inspired by a recently reported synthesis of armchair graphene sheets that relied on a benzannulation and Scholl oxidation of a poly(p-phenylene ethynylene), the same strategy is applied on a cyclic substrate with a short, but well defined CNT as target structure. Herein we report the synthesis of a derivatized [12]cyclo-para-phenylene acetylene ([12]CPPA) that was accessible employing a Sonogashira macro-cyclization. The obtained macrocycle is the largest [n]CPPA reported to date and displays bright turquoise fluorescence with a large quantum yield of 77%. The [12]CPPA can be transformed by a 12-fold benzannulation that converts each alkyne to a naphthalene and therefore allows formation of an armchair [12,12] CNT precursor. The final 72-fold Scholl oxidation to the [12,12] CNT turned out to be challenging and its optimization requires an improved synthetic strategy to produce large quantities of the final precursor. The developed approach poses a potential break through strategy for the production of CNTs and certainly incentivizes synthetic chemists to apply the same methodology for various conjugated macrocycles.

Imidazolium-decorated Bis-cyanostilbene Macrocycle: An Effect Fluorescence Sensor for Pesticide Starane.

Fluorescence sensors for complicated molecules such as pesticides were paid much attention lately due to the merits of simple operation, high sensitivity and selectivity, and in-situ detection. In this work, a novel fluorescent sensor for pesticide starane was prepared based on imidazolium-decorated bis-cyanostilbene macrocycle (IBM). IBM exhibited the obvious "turn-on" fluorescence change from dark blue-green to bright blue after sensing starane with the high sensing selectivity among 28 kinds of guests. The detecting limitation was as low as 0.011 µM, which was the lowest one in literatures. The sensing mechanism was confirmed as that starane was located in cavity of IBM based on the molecular interaction of multiple hydrogen bonds, π-π stacking and hydrophobic interaction. The application experiments suggested that starane was examined well on test paper with good selectivity and was quantitatively detected in water samples, implying the good real-time and in-situ application potential for IBM on sensing starane in real environment and daily life.

Facile synthesis of a new chiral polyimine macrocycle and its application for enantioseparation in high-performance liquid chromatography.

Macrocyclic compounds such as crown ethers and cyclodextrins play an important role in the field of chromatography and show excellent separation performance. The design of simple and convenient methods for the efficient synthesis of novel chiral macrocycles for chromatographic separation is of great significance. In this work, a novel chiral polyimine macrocycle (PIMC) was designed and synthesized by the simply one-step reaction of 2,6-diformyl-4-tert-butylphenol with (S)-(-)-1,2-propanediamine. Then, it was bonded onto silica by the thiol-ene click reaction to construct a new chiral stationary phase (CSP) for high-performance liquid chromatography (HPLC). The chiral separation performance of the proposed CSP was examined by separating various racemates in the normal-phase (NP) and reversed-phase (RP) HPLC. In total, twelve and nine racemates, including ethers, esters, amines, alcohols, organic acids, ketones, and epoxides, were separated to varying degrees via NP-HPLC and RP-HPLC, respectively, Moreover, the CSP offered good chiral separation complementarity to Chiralcel OD-H and Chiralpak AD-H columns for resolution of these test racemates, and it can separate several racemic compounds that either cannot be separated or cannot be separated well be separated by the two commercially available columns. After the column was used for hundreds of injections, the relative standard deviations of the retention time and resolution were below 0.56 % and 0.45 %, respectively, showing the good reproducibility and stability of the CSP. This study provides a simple and convenient approach to synthesize a novel chiral macrocycle and CSP and also indicates the broad application prospects of such chiral PIMCs in HPLC chiral separation.

Probing the Topological Effects on Stability Enhancement and Therapeutic Performance of Protein Bioconjugates: Tadpole, Macrocycle versus Figure-of-Eight.

Chemical topology provides a unique dimension for making therapeutic protein bioconjugates with native structure and intact function, yet the effects of topology remain elusive. Herein, the design, synthesis, and characterization of therapeutic protein bioconjugates in three topologies (i.e., tadpole, macrocycle, and figure-of-eight), are reported. The interferon α2b (IFN) and albumin binding domain (ABD) are selected as the model proteins for bioconjugation and proof-of-concept. The biosynthesis of these topological isoforms is accomplished via direct expression in cells using SpyTag-SpyCatcher chemistry and/or split-intein-mediated ligation for topology diversification. The corresponding topologies are proven with combined techniques of LC-MS, SDS-PAGE, and controlled proteolytic digestion. While the properties of these topological isoforms are similar in most cases, the figure-of-eight-shaped bioconjugate, f8-IFN-ABD, exhibits the best thermal stability and anti-aggregation properties along with prolonged half-life and enhanced tumor retention relative to the tadpole-shaped control, tadp-IFN-ABD, and the macrocyclic control, c-IFN-ABD, showcasing considerable topological effects. The work expands the topological diversity of proteins and demonstrates the potential advantages of leveraging chemical topology for functional benefits beyond multi-function integration in protein therapeutics.

Beyond Single-Cycle Autonomous Molecular Machines: Light-Powered Shuttling in a Multi-Cycle Reaction Network.

Biomolecular machines autonomously convert energy into functions, driving systems away from thermodynamic equilibrium. This energy conversion is achieved by leveraging complex, kinetically asymmetric chemical reaction networks that are challenging to characterize precisely. In contrast, all known synthetic molecular systems in which kinetic asymmetry has been quantified are well described by simple single-cycle networks. Here, we report on a unique light-driven [2]rotaxane that enables the autonomous operation of a synthetic molecular machine with a multi-cycle chemical reaction network. Unlike all prior systems, the present one exploits a photoactive macrocycle, which features a different photoreactivity depending on the binding sites at which it resides. Furthermore, E to Z isomerization reverses the relative affinity of the macrocycle for two binding sites on the axle, resulting in a multi-cycle network. Building on the most recent theoretical advancements, this work quantifies kinetic asymmetry in a multi-cycle network for the first time. Our findings represent the simplest rotaxane capable of autonomous shuttling developed so far and offer a general strategy to generate and quantify kinetic asymmetry beyond single-cycle systems.

Preparation and evaluation of a 1,1'-bi-2-naphthol-based chiral macrocycle bonded silica chiral stationary phase for high performance liquid chromatography.

Macrocycles play vital roles in supramolecular chemistry and chromatography. 1,1'-Bi-2-naphthol (BINOL)-based chiral polyimine macrocycles are an emerging class of chiral macrocycles that can be constructed by one-step aldehyde-amine condensation of BINOL derivatives with other building blocks. These macrocycles exhibit good characteristics, such as facile preparation, rigid cyclic structures, multiple chiral centers, and defined molecular cavities, that make them good candidates as new chiral recognition materials for chromatographic enantioseparations. In this study, a BINOL-based [2+2] chiral polyimine macrocycle was synthesized by one-step condensation of enantiopure (S)-2,2'-dihydroxy-[1,1'-binaphthalene]-3,3'-dicarboxaldehyde with (1R,2R)-1,2-diaminocyclohexane. The product was modified with 5-bromo-1-pentene and then attached to thiolated silica using click chemistry to construct a new chiral stationary phase (CSP). The enantioselectivity of the new CSP was explored by separating various racemates under normal phase (NP) and reversed phase (RP) high performance liquid chromatography (HPLC). Thirteen racemates and eight racemates were enantioseparated under the two separation modes, respectively, including chiral alcohols, phenols, esters, ketones, amines, and organic acids. Among them, nine racemates achieved baseline separation under NP-HPLC and seven racemates achieved baseline separation under RP-HPLC. High resolution separation was observed with benzoin (Rs = 5.10), epinephrine (Rs = 4.98), 3-benzyloxy-1,2-propanediol (Rs = 4.42), and 4,4'-dimethylbenzoin (Rs = 4.52) in NP-HPLC, and with 4-methylbenzhydrol (Rs = 4.72), benzoin ethyl ether (Rs = 3.79), 1-phenyl-1-pentanol (Rs = 3.68), and 1-(3-bromophenyl)ethanol (Rs = 3.60) in RP-HPLC. Interestingly, the CSP complemented Chiralcel OD-H, Chiralpak AD-H, and CYCLOBOND I 2000 RSP columns for resolution of these test racemates, separating several racemic compounds that could not be well separated by the three commercially available columns. The influences of injected sample amount on separation were also evaluated. It was found that the column exhibited excellent stability and reproducibility after hundreds of injections, and the relative standard deviations (n = 5) of the retention time and resolution were less than 0.49% and 0.69%, respectively. This study indicates that the BINOL-based chiral macrocycle has great potential for HPLC enantioseparation.

Synthesis, Structure, Spectral, Redox, and Theoretical Studies of Sterically Crowded Decaaryl Triphyrin(2.1.1)s.

First examples of sterically crowded ß- and meso-arylated decaaryl triphyrin(2.1.1)s were synthesized by reacting ß-hexabromo meso-tetraaryl triphyrin(2.1.1) with five different aryl boronic acids in THF/toluene/H2O (1:1:1) in the presence of catalytic amount of Pd(PPh3)4/Na2CO3 at 80 °C for 12-24 h. The X-ray structure obtained for one of the decaaryl triphyrin(2.1.1)s revealed that the macrocycle exhibited saddle type of distortion due to steric crowding by bulky aryl substituents introduced at the six ß-carbons of meso-tetraaryl triphyrin(2.1.1) unlike almost planar structure observed for ß-unsubstituted meso-tetraaryl triphyrin(2.1.1). The absorption bands of decaaryl triphyrin(2.1.1)s were broadened and bathochromically shifted compared to meso-tetraaryl triphyrin(2.1.1) and the redox potentials were dependent on the kind of aryl substituents present at the ß-pyrrole carbons in decaaryl triphyrin(2.1.1)s. DFT and TD-DFT studies helped in understanding the alteration in the structure, spectral, and redox properties in decaaryl triphyrin(2.1.1)s compared to meso-tetraaryl triphyrin(2.1.1).

Rigid Macrocycle Metal Complexes as CXCR4 Chemokine Receptor Antagonists: Influence of Ring Size.

Understanding the role of chemokine receptors in health and disease has been of increasing interest in recent years. Chemokine receptor CXCR4 has been extensively studied because of its defined role in immune cell trafficking, HIV infection, inflammatory diseases, and cancer progression. We have developed high affinity rigidified CXCR4 antagonists that incorporate metal ions to optimize the binding interactions with the aspartate side chains at the extracellular surface of the CXCR4 chemokine receptor and increase the residence time. Cross- and side-bridged tetraazamacrocylic complexes offer significant advantages over the non-bridged molecular structures in terms of receptor affinity, potential for radiolabelling, and use in therapeutic applications. Our investigation has been extended to the influence of the ring size on bridged tetraazamacrocyclic compounds with the addition of two novel chelators (bis-cross-bridged homocyclen and bis-cross-bridged cyclen) to compare to the bis-bridged cyclam, along with novel metal complexes formed with copper(II) or zinc(II). The in vitro biological assays showed that all of the zinc(II) complexes are high affinity antagonists with a marked increase in CXCR4 selectivity for the bis-cross-bridged cyclen complex, whereas the properties of the copper(II) complexes are highly dependent on metal ion geometry. X-ray crystal structural data and DFT computational studies allow for the rationalisation of the relative affinities and the aspartate residue interactions on the protein surface. Changing the ring size from 14-membered can increase the selectivity for the CXCR4 receptor whilst retaining potent inhibitory activity, improving the key pharmacological characteristics.

Columnar Organization of Nonalternant Fluorinated Dehydrobenzannulenes.

Two new partially fluorinated dehydrobenzannulenes have been prepared by inter- and intramolecular oxidative homocoupling of diyne precursors. These systems contain fluorinated and nonfluorinated arene rings in a non-alternant arrangement. Both macrocycles are roughly planar and organize into extended columns in the solid state. The assembly of these columns is mediated by the combination of dispersion interactions, slipped [π···π] stacking interactions of the perfluorinated rings with each other, and their association with the nonfluorinated rings in the molecules of the neighboring macrocycles. These results suggest that partial fluorination of dehydrobenzannulenes can serve as a versatile motif for their assembly into columnar superstructures.

Aqueous colloid flow batteries with nano Prussian blue.

Flow battery is a safe and scalable energy storage technology in effectively utilizing clean power and mitigating carbon emissions from fossil fuel consumption. In the present work, we demonstrate an aqueous colloid flow battery (ACFB) with well-dispersed colloids based on nano-sized Prussian blue (PB) cubes, aiming at expanding the chosen area of various nano redox materials and lowering the cost of chemicals. Taking advantage of the two redox pairs of PB, the developed all-PB cell employing a low-cost dialysis membrane with the synthesized PB on both sides displays an open-circuit voltage (OCV) of 0.74 V. Moreover, when paired with an organic tetra pyridine macrocycle the cell with PB as positive electrolyte exhibits an OCV of 1.33 V and a capacity fade rate of 0.039 %/cycle (0.8 %/day). Redox-active colloids exhibit enduring physicochemical stability, with no evident structural or morphological changes after extensive cycling, highlighting their potential for cost-effective and reliable ACFB energy storage.

La percepción de cansancio en decatlonistas, en diferentes etapas del macrociclo de entrenamiento

El control del comportamiento de la percepción de cansancio a lo largo del macrociclo de entrenamiento en decatlonistas constituye un indicador para la valoración del proceso de asimilación psicofísica del trabajo realizado acorde a la etapa del macrociclo de entrenamiento por la que transita el atleta. Sin embargo, el insuficiente conocimiento sobre el tema en el decatlón ha limitado el uso de este indicador en el control psicológico de la preparación en este deporte. El objetivo de este trabajo consiste en determinar el comportamiento de la percepción de cansancio en las diferentes etapas del macrociclo de entrenamiento, en decatlonistas de la selección nacional de atletismo de Cuba. Es un estudio descriptivo, en el que se aplica la entrevista para un diagnóstico inicial y la Escala de Borg (modificada), para la medición de la percepción de cansancio. Fueron realizadas 416 mediciones de la percepción de cansancio, durante las etapas de preparación física, general, especial y competitiva. Como principales resultados, la percepción de cansancio aumentó en la etapa de preparación física general en una magnitud de 3.48, en la etapa especial en un 3.43 y en la competitiva en un 2.56. La percepción de cansancio en los decatlonistas estudiados aumentó, significativamente, posterior a las cargas de entrenamiento en cada una de las etapas estudiadas y disminuyó, a medida que avanzó el macrociclo de entrenamiento. La etapa competitiva resultó ser aquella de menor cansancio percibido pre- y poscarga, y la de preparación física general, la de mayor aumento en este proceso.

O controle do comportamento da percepção da fadiga ao longo do macrociclo de treinamento em decatletas constitui um indicador para a avaliação do processo de assimilação psicofísica do trabalho realizado de acordo com a etapa do macrociclo de treinamento pela qual o atleta passa. Contudo, o conhecimento insuficiente sobre o tema no decatlo tem limitado a utilização deste indicador no controle psicológico da preparação neste esporte. O objetivo deste trabalho é determinar o comportamento da percepção da fadiga nas diferentes etapas do macrociclo de treinamento, em decatlonistas da seleção cubana de atletismo. Trata-se de um estudo descritivo, no qual é aplicada a entrevista para diagnóstico inicial e a Escala de Borg (modificada) para mensurar a percepção de fadiga. Foram realizadas 416 medidas de percepção de fadiga durante as etapas de preparação física, geral, especial e competitiva. Como principais resultados, a percepção de fadiga aumentou na etapa de preparação física geral em uma magnitude de 3,48, na etapa especial em 3,43 e na etapa competitiva em 2,56. A percepção de fadiga no decatleta estudado aumentou significativamente após as cargas de treinamento em cada uma das etapas estudadas e diminuiu à medida que o macrociclo de treinamento avançava. A etapa competitiva acabou sendo a que apresentou menor fadiga percebida pré e pós-carga, e a etapa de preparação física geral, a que apresentou maior aumento nesse processo.

The control of the behavior of the perception of tiredness throughout the training macrocycle in decathletes constitutes an indicator for the assessment of the process of psychophysical assimilation of the work carried out according to the stage of the training macrocycle through which the athlete goes. However, insufficient knowledge on the subject in the decathlon has limited the use of this indicator in the psychological control of preparation in this sport. The objective of this work is to determine the behavior of the perception of tiredness in the different stages of the training macrocycle, in tiredness of the Cuban national athletics team. It is a descriptive study, in which the interview is applied for an initial diagnosis and the Borg Scale (modified) to measure the perception of tiredness. 416 measurements of the perception of tiredness were carried out during the stages of general, special and competitive physical preparation. As the main results, the perception of tiredness increased in the general physical preparation stage by a magnitude of 3.48, in the special stage by 3.43 and in the competitive stage by 2.56. The perception of tiredness in the decathletes studied increased significantly after the training loads in each of the stages studied and decreased as the training macrocycle progressed. The competitive stage turned out to be the one with the least perceived pre- and post-load tiredness, and the general physical preparation stage was the one with the greatest increase in this process.

Isolation, Structure Elucidation, and Biological Activity of the Selective TACR2 Antagonist Tumonolide and its Aldehyde from a Marine Cyanobacterium.

The macrocyclic tumonolide (1) with enamide functionality and the linear tumonolide aldehyde (2) are new interconverting natural products from a marine cyanobacterium with a peptide-polyketide skeleton, representing a hybrid of apratoxins and palmyrolides or laingolides. The planar structures were established by NMR and mass spectrometry. The relative configuration of the stereogenically-rich apratoxin-like polyketide portion was determined using J-based configuration analysis. The absolute configuration of tumonolide (1) was determined by chiral analysis of the amino acid units and computational methods, followed by NMR chemical shift and ECD spectrum prediction, indicating all-R configuration for the polyketide portion, as in palmyrolide A and contrary to the all-S configuration in apratoxins. Functional screening against a panel of 168 GPCR targets revealed tumonolide (1) as a selective antagonist of TACR2 with an IC50 of 7.0 µM, closely correlating with binding affinity. Molecular docking studies established the binding mode and rationalized the selectivity for TACR2 over TACR1 and TACR3. RNA sequencing upon treatment of HCT116 colorectal cancer cells demonstrated activation of the pulmonary fibrosis idiopathic signaling pathway and the insulin secretion signaling pathway at 20 µM, indicating its potential to modulate these pathways.

Designed Synthesis of an Aluminum Molecular Ring Based Rotaxane and Polyrotaxane.

Mechanically interlocked molecules, such as rotaxanes, have drawn significant attention within supramolecular chemistry. Although a variety of macrocycles have been thoroughly explored in rotaxane synthesis, metal-organic macrocycles remain relatively under-investigated. Aluminum molecular rings, with their inner cavities and numerous binding sites, present a promising option for constructing rotaxanes. Here, we introduce an innovative "ring-donor···axle-acceptor" motif utilizing Al8 molecular rings, enabling the stepwise assembly of molecules, complexes, and polymers through tailored coordination chemistry. This novel approach can not only be applied to macrocycle-based systems like catenanes but also enhance specific functionalities progressively.

Post-Synthetic Modification of Calix[4]arene Framework by Iridium-Mediated Alkyne Insertion into an Inert C-C Bond: A Novel Strategy for Unsymmetrical Macrocycles.

As a novel synthetic method for unsymmetrical macrocycles, we herein developed a post-synthetic modification of calix[4]arenes by insertion of a terminal alkyne into an inert C(methylene)-C(aryl) bond of the macrocyclic framework. In this transformation, C-iridated calix[4]arenes, readily synthesized through C-H bond activation of the parent calix[4]arene, undergoes C(methylene)-C(aryl) bond cleavage followed by insertion of an alkyne to provide a ring-expanded calix[4]arene complex. Removal of the iridium metal from the resulting complex was readily accomplished by a simple treatment with an acid. The developed sequential method affords novel unsymmetrical, monofunctionalized macrocyclic compounds via 3 steps from the parent calix[4]arene in good yield. The unique unsymmetrical structures of the alkyne-inserted macrocycles were evaluated by X-ray single crystal analyses. On the basis of theoretical calculations, we propose a reaction mechanism involving an uncommon C-C bond cleavage step through δ-carbon elimination for the ring enlargement process.

Facile Synthesis and Global Aromaticity of Aza-Superbenzene and Aza-Supernaphthalene at Different Oxidation States.

All-benzenoid polycyclic aromatic hydrocarbons or macrocycles usually display localized aromaticity. On the other hand, incorporation of quinoidal units into the skeleton could lead to effective electron delocalization and global (anti)aromaticity. In this work, fully π-conjugated macrocycle 1 and bismacrocycle 2 containing both para-quinodimethane and triphenylamine units are efficiently synthesized mainly through intermolecular Friedel-Crafts alkylation reaction. They can be considered as a tetraazasuperbenzene and a hexaazasupernaphthalene, respectively, due to their similar geometry and electronic structures to the benzene and naphthalene. X-ray crystallographic analyses reveal a largely planar geometry for both 1 and 2 and variable-temperature NMR measurements disclose slow dynamic processes owing to restricted ring flipping of the phenyl rings. 1 and 2 can be easily oxidized into higher-oxidation-state species. NMR and theoretical calculations indicate that 12+ and 14+ show global anti-aromaticity and aromaticity, respectively, with a dominant 32π and 30π conjugation pathway, while for the bismacrocycle 2, its dication 22+, tetracation 24+ and hexacation 26+ exhibit global aromaticity, antiaromaticity, and aromaticity with a 54π, 52π and 50π conjugation pathway along the outermost backbone, respectively.

Exploring the Spatial Arrangement of Simple 18-Membered Hexaazatetraamine Macrocyclic Ligands in Their Metal Complexes.

Hexaazamacrocyclic Schiff bases have been extensively combined with lanthanoid (Ln) ions to obtain complexes with a highly axial geometry. However, the use of flexible hexaazatetraamine macrocycles containing two pyridines and acyclic spacers is rather uncommon. Accordingly, we obtained [DyL(OAc)2]OAc·7H2O·EtOH and [DyLMe2(Cl)2]Cl·2H2O, where L and LMe2 are the 18-membered macrocycles 3,6,10,13-tetraaza-1,8(2,6)-dipyridinacyclotetradecaphane and 3,10-dimethyl-3,6,10,13-tetraaza-1,8(2,6)-dipyridinacyclotetradecaphane, respectively, which contain ethylene and methylethylene spacers between their N3 moieties. [DyL(OAc)2]OAc·7H2O·EtOH represents the first crystallographically characterized lanthanoid complex of L, while [DyLMe2(Cl)2]Cl·2H2O contributes to increasing the scarce number of LnIII compounds containing LMe2. Furthermore, the crystal structure of L·12H2O was solved, and it was compared with those of other related macrocycles previously published. Likewise, the crystal structures of the DyIII complexes were compared with those of the lanthanoid and d-metal complexes of other 18-membered N6 donor macrocycles. This comparison showed some effect of the spacers employed, as well as the influence of the size of the ancillary ligands and the metal ion. Additionally, the distinct folding behaviors of these macrocycles influenced their coordination geometries. Moreover, the luminescent properties of [DyL(OAc)2]OAc·7H2O·EtOH and [DyLMe2(Cl)2]Cl·2H2O were also investigated, showing that both complexes are fluorescent, with the emission being sensitized by the ligands.