Self-Assemblies of Carboxylic Acid Derivatives with Different Symmetry: Adjusting by Solvent and Guest Molecules.

In this research, the self-assembly behaviors of two different symmetry carboxylic acid derivatives ( and ) regulated by solvent and guest molecule (coronene, COR) were explored at the liquid/solid interface by scanning tunneling microscopy, and the formation mechanism was investigated by density functional theory. In 1-phenyloctane, only molecules dissolved with extremely low concentration and self-assembled into a honeycomb structure and a new strip structure, while could not. In 1-heptanoic acid, and were easily dissolved, in which formed a regular row structure and formed a tetragonal structure, respectively.

Study on 2D Molecular Networks of Flexible Pentacarboxylic Acid Ligands Induced by Ether Bonds in Response to Selective Guest Inclusion.

The flexibility of ligands allows for their bending, twisting, or rotation to adopt various conformations, leading to distinct symmetries during the self-assembled process. Flexible aromatic acid ligands modified by ether bonds are a promising type of self-assembled module when it comes to surfaces. Here, two pentacarboxylic acid ligands (HL1 and HL2) with minor skeleton differences have successfully self-assembled into disparate porous networks on the graphite surface and demonstrated excellent potential for the inclusion of guest molecules.

Two-dimensional self-assembly and co-assembly of two tetracarboxylic acid derivatives investigated by STM.

In this work, the two-dimensional self-assembly and co-assembly behaviors of two tetracarboxylic acid derivatives (HBDETP and HBTB) were investigated by scanning tunneling microscopy (STM). HBDETP molecules self-assembled into linear nanostructures, and HBTB molecules formed lamellar and tetragonal nanostructures. The formation of a HBDETP/HBTB co-assembly nanostructure was closely related to the deposition sequence of HBDETP and HBTB on highly oriented pyrolytic graphite (HOPG).

A Solution-Processable Porphyrin-Based Hydrogen-Bonded Organic Framework for Photoelectrochemical Sensing of Carbon Dioxide.

Detecting CO in complex gas mixtures is challenging due to the presence of competitive gases in the ambient atmosphere. Photoelectrochemical (PEC) techniques offer a solution, but material selection and specificity remain limiting. Here, we constructed a hydrogen-bonded organic framework material based on a porphyrin tecton decorated with diaminotriazine (DAT) moieties.

The self-assembly of a pair of low-symmetry tetracarboxylic acid molecules and their co-assembly with bridging molecules at the liquid-solid interface.

The supramolecular self-assembly behavior of a pair of low-symmetry tetracarboxylic acid molecules (HOBDB and HADDI) and their co-assembly behavior with TMA as a bridging molecule were studied at the liquid-solid interface. Scanning tunneling microscope (STM) observations revealed that HOBDB and HADDI molecules both tend to form O-shaped dimers but end up forming different types of self-assembly structures. We also investigated the construction of two-component co-assembly structures by mixing HOBDB or HADDI molecules with bridging molecules such as TMA.

Sheet-like 2D Manganese(IV) Complex with High Photothermal Conversion Efficiency.

We report a stable, water-soluble, mononuclear manganese(IV) complex [Mn(H)]·5HO (Mn-HDCL) that acts as an efficient photothermal material. This system is based on a hexahydrazide clathrochelate ligand (/HDCL) and is obtained via an efficient one-pot templated synthesis that avoids the need for harsh reaction conditions. Scanning tunneling microscopy images reveal that Mn-HDCL exists as a 2D sheet-like structure.

Hydrogen-Bonded Organic Framework Ultrathin Nanosheets for Efficient Visible-Light Photocatalytic CO Reduction.

Post-modification of robust guanine-quadruplex-linked 2,2'-pyridine-containing HOF-25 with Ni(ClO )  ⋅ 6 H O followed by exfoliation using sonication method affords hydrogen-bonded organic framework (HOF) nanosheets (NSs) of HOF-25-Ni in the yield of 56 %. TEM and AFM technologies disclose the ultrathin nature of HOF-25-Ni NSs with thickness of 4.4 nm.

Insight into the Nanotribological Mechanism of Two-Dimensional Covalent Organic Frameworks.

Two-dimensional (2D) materials are promising in reducing friction-induced energy loss and wear in automotive and electronics industries because of their superior tribological performance. As a kind of organic 2D materials, the structure and functionality of covalent organic frameworks (COFs) are much easier to tailor compared to other inorganic 2D materials, which expand their potential application in a Micro-Electro-Mechanical System (MEMS). In this manuscript, several kinds of COFs are synthesized and characterized on the surface of highly oriented pyrolytic graphite (HOPG) to investigate the nanotribological mechanism of organic 2D materials.

Minor adjustments in the chemical structures of pyridine derivatives induced different co-assemblies by O-H⋯N hydrogen bonds.

The co-adsorption behaviours of aromatic carboxylic acids with various pyridine derivatives were investigated with scanning tunneling microscopy and density functional theory. Surprisingly, minor adjustments in the chemical structures of the pyridine derivatives, such as the relative position of the nitrogen atom or the lengths of the side chains on the backbone would evidently affect the intermolecular O-H⋯N hydrogen bonds and further form various co-adsorption structures.

Co-assembly Behaviors of Flavonol Derivatives Induced by a Pyridine Derivative on HOPG via Hydrogen Bonding and Van der Waals Forces.

In this paper, two new flavonol derivatives, 2-(4-(dodecyloxy)phenyl)-3-hydroxyflavone () and 2-(3,5-bis(dodecyloxy)phenyl)-3-hydroxyflavone (), were synthesized to investigate the respective self-assembly behaviors at the liquid/solid interface by scanning tunneling microscopy. In addition, a linear pyridine derivative with acetylene groups called was added to regulate the assembly of and , individually. However, only molecules successfully co-assembled into grid structures with molecules.

Effects of functional groups and side chains on assembly of "X"-shaped new aggregation-induced emission molecules.

The self-assembly properties of aggregation-induced emission molecules play important roles in electroluminescence devices and fluorescence sensors because noncovalent interactions in self-assembly structures would accelerate the excitation energy consumption. However, there are only few studies to explore their self-assembly properties on the interface and there is still a great need for further understanding self-assembled mechanisms from the viewpoint of molecular design. Here, we presented three X-shaped aggregation-induced emission molecules X1, X2 and X3, which decorated with different functional groups and alkyl side chains.

Regulation of the Assembled Structure of a Flexible Porphyrin Derivative Containing Tetra Isophthalic Acids by Coronene or Different Pyridines.

Based on previous research, a new coassembly formed by a porphyrin derivative (IPETPP), which contains a flexible substituent of -phthalic acid, is observed with coronene (COR) molecules at a higher concentration. Besides, a fresh IPETPP self-assembly formed at a lower concentration and another new coassembly with COR molecules are obtained. Moreover, the addition of a series of bipyridines alters the diamond arrangement of IPETPP, which enhances the stability of the two-component structures.

Self-Assembly of Triphenylamine Macrocycles and Co-assembly with Guest Molecules at the Liquid-Solid Interface Studied by STM: Influence of Different Side Chains on Host-Guest Interaction.

The side chains of macrocyclic molecules have a non-negligible effect on the two-dimensional (2D) supramolecular networks at the liquid-solid interface. In this study, we investigate the self-assembly behaviors of two conjugated triphenylamine macrocycles modified with different alkyl chains and construct the host-guest supramolecular nanopatterns on the highly oriented pyrolytic graphite with a scanning tunneling microscope. In combination with density functional theory calculations, how different side chains affect the host-guest interaction is discussed.

The self-assembly and pyridine regulation of a hydrogen-bonded dimeric building block formed by a low-symmetric aromatic carboxylic acid.

The supramolecular self-assembly behavior of a low-symmetric aromatic carboxylic acid molecule (HBHB) and its co-assembly behavior with a series of pyridine molecules (BPD, BPDYB and TPDYB) were studied at the heptanoic acid/HOPG liquid-solid interface. Scanning tunneling microscopy (STM) observations revealed that HBHB molecules tend to form dimeric building blocks which then assemble into a close-packed structure. BPD, BPDYB and TPDYB pyridine molecules were all able to form a stable two-component co-assembled structure with the HBHB molecule, and in these co-assembled structures, the HBHB molecule still takes the form of a dimer.

Effects of Halogenation on the Benzotriazole Unit of Non-Fullerene Acceptors in Organic Solar Cells with High Voltages.

Non-fullerene acceptors (NFAs) can be simply divided into three categories: A-D-A, A-DA'D-A, and A-A-D-A-A according to their chemical structures. Benefiting from the easily modified 1,1-dicyanomethylene-3-indanone end groups, the halogenation on the first two types of materials has been proved to be very effective to modulate their optoelectronic properties and improve their photovoltaic performance. Hence, in this work, we systematically investigate the effect of halogenation on the classic NFA molecule of , which has the linear A-A-D-A-A-type backbone.

Diverse Self-assembly Structures of a Macrocycle Revealed with STM by Adjusting the Solution Concentration.

The macrocyclic molecule [3]C TT-TPA was synthesized by a Stille coupling reaction through alternately connecting 4,7-bisthienyl-2,1,3-thienothiazole and triphenylamine units. The concentration-dependent self-assembly structures of [3]C TT-TPA were explored in liquid/solid interface by scanning tunneling microscopy and density functional theory. After increasing the solution concentration, five different nanostructures were constructed and the molecular packing densities were gradually enhanced.

Regulation of a Porphyrin Derivative Containing Two Symmetric Benzoic Acids by Different Pyridines.

A porphyrin derivative called 5,15-di(4-carboxyphenyl)porphyrin (HDCPp) with carboxyl groups successfully self-assembled on a highly oriented pyrolytic graphite (HOPG) surface and its co-assembly structures with three kinds of pyridine molecules were investigated by scanning tunneling microscopy (STM) with atomic resolution. HDCPp arranged in a long-range ordered structure, and both 1,4-bis (pyridin-4-ylethynyl) benzene (BisPy), 4,4'-bipyridine (BP) and 1,3,5-tris(pyridin-4-ylethynyl) benzene (TPYB) molecules successfully regulated the host molecules as guest molecules. The well-organized model optimized by density functional theory (DFT) calculations reveals the detailed behavior of the assembly characteristics and regulation of porphyrin derivatives, which is helpful for the research and development of solar cells and nanodevices.

Structural and Nanotribological Properties of a BODIPY Self-Assembly.

Boron-dipyrromethenes (BODIPY) are promising functional dyes, whose exceptional optical properties are closely related to their supramolecular assembly. Herein, the self-assembly of a BODIPY derivative functionalized with uracil groups is explicitly and thoroughly investigated by using scanning tunneling microscopy (STM). Based on the simulation and calculation by density functional theory (DFT) method, it can be concluded that the construction of ordered self-assembly structure is attributed to the formation of hydrogen bonds between uracil groups.

Tricyclic or Pentacyclic D Units: Design of D-π-A-Type Copolymers for High Organic Photovoltaic Cells.

Although there are several electron-donating (D) units, only the classic benzo[1,2-b:4,5-b']dithiophenes (BDT) unit was utilized to develop D-π-A-type copolymers for high-voltage organic photovoltaic (OPV) cells. Hence, in this work, we chose two tricyclic D units, BDT and benzo[1,2-b:4,5-b']difurans (BDF), together with one pentacyclic ring, dithieno[2,3-d;2',3'-d']benzo[1,2-b;4,5-b']dithiophenes (DTBDT), to comprehensively study the effect of different D units on the optoelectronic properties and photovoltaic performance. By copolymerized with the benzo[1,2,3]triazole (BTA) electron-accepting unit, the final copolymers , , and were combined with a nonfullerene acceptor (NFA) according to the "Same-A-Strategy.

Insight Into the Superlubricity and Self-Assembly of Liquid Crystals.

Liquid crystals are promising molecular materials in the application of lubrication. Herein, the microscale solid superlubricity is accomplished by the construction of uniform and ordered self-assembly of several liquid crystals. The self-assembly structures on a highly oriented pyrolytic graphite (HOPG) surface are explicitly revealed by using scanning tunneling microscopy (STM).

π-Conjugated Macrocycle Host-Guest Coassembly with C60 on HOPG.

Two kinds of π-conjugated macrocycles with aggregation-induced emission (AIE) properties were investigated by scanning tunneling microscopy (STM) to elucidate their self-assembly behaviors and interaction with C60 on a highly oriented pyrolytic graphite (HOPG) surface. Both TPEMC and TPEMCS could self-assemble into orderly cavity structures. However, C60 guest molecules could only successfully enter the cavity of TPEMC to form a stable TPEMC + C60 host-guest coassembly structure.

Progress in self-assemblies of macrocycles at the liquid/solid interface.

Macrocyclic self-assemblies have gained great interest for diversified structures and potential applications, such as catalysis, magnetism, photovoltaic devices, organic light-emitting diodes. Macrocycles can present regular assembly systems at the liquid/solid interface due to the-conjugated structures. Furthermore, suitable guest molecules can be selected for constructing multi-component supramolecular co-assemblies.

Fabrication of High Organic Solar Cells with a Non-Halogenated Solvent and the Effect of Substituted Groups for "Same-A-Strategy" Material Combinations.

We report a class of high-voltage organic solar cells (OSCs) processed by the environmentally friendly solvent tetrahydrofuran (THF), where four benzotriazole (BTA)-based p-type polymers (, , , and ) and a BTA-based small molecule are applied as p-type and n-type materials, respectively, according to "Same-A-Strategy" (SAS). The single-junction OSCs based on all four material blends exhibit a high open-circuit voltage () above 1.10 V.