Adamantane Core Research Articles

Network topology diversification of porous organic salts.

Hydrogen-bonded organic frameworks (HOFs) are porous organic materials constructed via hydrogen bonds. HOFs have solubility in specific high-polar organic solvents. Therefore, HOFs can be returned to their components and can be reconstructed, which indicates their high recyclability. Network topologies, which are the frameworks of porous structures, control the pore sizes and shapes of HOFs. Therefore, they strongly affect the functions of porous materials. However, hydrogen bonds are usually weak interactions, and the design of the intended network topology in HOFs from their components has been challenging. Porous organic salts (POSs) are an important class of HOFs, are hierarchically constructed via strong charge-assisted hydrogen bonds between sulfonic acids and amines, and therefore are expected to have high designability of the porous structure. However, the network topology of POSs has been limited to only dia-topology. Here, we combined tetrasulfonic acid with the adamantane core (4,4',4'',4'''-(adamantane-1,3,5,7-tetrayl)tetrabenzenesulfonic acid; AdPS) and triphenylmethylamines with modified substituents in para-positions of benzene rings (TPMA-X, X = F, methyl (Me), Cl, Br, I). We changed the steric hindrance between the adamantane and substituents (X) in TPMA-X and obtained not only the common dia-topology for POSs but also rare sod-topology, and lon- and uni-topologies that are formed for the first time in HOFs. Changing template molecules under preparation helped in successfully isolating the porous structures of AdPS/TPMA-Me with dia-, lon-, and sod-topologies which exhibited different gas adsorption properties. Therefore, for the first time, we demonstrated that the steric design of HOF components facilitated the formation, diversification, and control of the network topologies and functions of HOFs.

ANTI-INFLAMMATORY AND ANALGESIC ACTIVITY OF AZAADAMANTANES - ANALOGUES OF AMANTADINE

The anti-inflammatory and analgesic activity of three azaadamantane analogues of amantadine 1 was investigated. The tested azaadamantanes containing nitrogen atoms in the polycyclic framework were: 5,7-dimethyl-1,3-diazaadamantane-6-one 2, 6-amino-5,7-dimethyl-1,3-diazaadamantane 3 and 7-amino-1,3,5-triazaadamantane 4. Experiments were carried out on male mice of CD1 and CBA lines. Compounds were administered intraperitoneally at doses of 20 and 50 mg/kg. Anti-inflammatory activity was studied on the standard models of inflammatory edema induced by histamine or concanavaline inflammation by injecting the phlogogens in the aponeurosis of the hind paw of mice. The analgesic activity was assessed using the hot plate and acetic writhing tests. It is shown that the introduction of heteroatoms into the adamantane core does not reduce the anti-inflammatory activity of diazaadamantanes (2, 3) and enhances that of triazaadamantane (4) compared to amantadine. Modification of the adamantane backbone with nitrogen atoms leads to a change in the analgesic properties of the molecule, which is manifested as hyperalgesia in the acetic writhing test. This phenomenon is presumably related to the effect of azaadamantanes on nocigenic transient receptor potential channels (TRPV1).

Incorporation of Coronene into Cage‐like Porous Organic Salts and Induction of its Room‐Temperature Phosphorescence in Air

AbstractCoronene emits phosphorescence only at cryogenic temperatures in the absence of oxygen. To achieve room‐temperature phosphorescence (RTP), coronene has been incorporated into various host materials to prevent non‐radiative deactivation of the incorporated molecules. Among host materials, crystalline porous materials homogeneously incorporate luminescent molecules and prevent their aggregation. Therefore, they have attracted attention as potential host materials. Although coronene incorporated into a crystalline porous material exhibited RTP in previous studies, the host material exhibited high affinity for oxygen, allowing the expression of RTP only under anoxic conditions. Therefore, RTP has not been achieved in air. Herein, we incorporate coronene into cage‐like sodalite‐type porous organic salts (s‐POSs) composed of tetrasulfonic acid with an adamantane core (4,4’,4’’,4’’’‐[adamantane‐1,3,5,7‐tetrayl]tetrabenzenesulfonic acid; AdPS) and triphenylmethylamines modified with substituents at the para‐position of the benzene rings (TPMA−X, X=methyl [Me], Br, I), which have low oxygen affinities and different degrees of heavy‐atom effects on incorporated coronene. The combination of the oxygen barrier due to the low affinity of s‐POSs for oxygen and the external heavy‐atom effect of bromine and iodine exposed on the pore surface enabled the incorporated coronene to exhibit RTP in air (phosphorescence lifetime with more than microseconds).

Controlled Vertical Transfer of Individual Au Atoms Using a Surface Supported Carbon Radical for Atomically Precise Manufacturing

To explore a proof-of-concept for atomically precise manufacturing (APM) using scanning probe microscopy (SPM), first principle theoretical calculations of atom-by-atom transfer from the apex of an SPM tip to an individual radical on a surface-bound organic molecule have been performed. Atom transfer is achieved by spatially controlled motion of a gold terminated tip to the radical. Two molecular tools for SPM-based APM have been designed and investigated, each comprising an adamantane core, a radical end group, and trithiol linkers to enable strong chemisorption on the Au(111) surface: ethynyl-adamantane-trithiol and adamantyl-trithiol. We demonstrate the details of controlled Au atom abstraction during tip approach toward and retraction from the radical species. Upon approach of the tip, the apical Au atom undergoes a transfer toward the carbon radical at a clearly defined threshold separation. This atomic displacement is accompanied by a net energy gain of the system in the range −0.5 to −1.5 eV, depending on the radical structure. In the case of a triangular pyramidal apex model, two tip configurations are possible after the tip atom displacement: (1) an Au atom is abstracted from the tip and bound to the C radical, not bound to the tip base anymore, and (2) apical tip atoms rearrange to form a continuous neck between the tip and radical. In the second case, subsequent tip retraction leads to the same final configuration as the first, with the abstracted Au atom bound to radical carbon atom of the molecular tool. For the less reactive adamantyl-trithiol radical molecular tool, Au atom transfer is less energetically favored, but this has the advantage of avoiding other apex gold atoms from rearrangement.

Cage-Like Sodalite-Type Porous Organic Salts Enabling Luminescent Molecule's Incorporation and Room-temperature Phosphorescence Induction in Air.

Expression of room-temperature phosphorescence (RTP) in organic materials requires complicated molecular design and specific intermolecular interactions, and therefore types of RTP materials are restricted. This work presents cage-like sodalite-type porous organic salts (s-POSs) as host materials for luminescent molecules to induce RTP, using tetrasulfonic acid with an adamantane core and triphenylmethylamines that are modified with substituents in the para-positions of benzene rings (TPMA-X). By adding a representative luminescent molecule (pyrene) to a reaction solution during construction of s-POSs, the molecule is incorporated in a facile manner. s-POSs with a heavy halogen atom (X: Iodine) on the pore surface give heavy atom effects, suppression of thermal vibration, and protection from oxygen, for the incorporated molecule, which induce its RTP even in air. This strategy can be applied to various luminescent molecules, which may lead to the achievement of RTP of various colors.

Metal‐ion sensor composed of self‐assembled monolayer of amine ligand formed by the use of molecular tripod

AbstractThe electrochemical ion‐sensor performance of the self‐assembled monolayer (SAM) of 3H‐imidazo[4,5‐b]pyridine, which is known as a metal ionophore, was examined using a triad composed of ferrocene, an ionophore, and a tripodal trithiol with adamantane core. The voltammetry of the SAM‐modified Au electrode showed a large positive change (280 mV) in the ferrocene oxidation potential via the addition of Pb2+, with a detection limit of 10–6 M. A Langmuir adsorption‐type analysis of the ion binding equilibrium suggested that as much as 70% of the imidazopyridine ligand was actually functioning as a Pb2+ ionophore on the SAM, whereas the rest of the ligand was uncomplexed because of the crowding of the molecules in the SAM. Control experiments using an analogous triad of monothiol revealed a strong advantage in using trithiol; thus, tripod‐shaped anchor is requisite for the ionophore to function well as a sensor.

Stable spontaneous orientation polarization by widening the optical band gap with 1,3,5,7-tetrakis(1-phenyl-1H-benzo[d]imidazol-2-yl)adamantane

1,3,5,7-Tetrakis(1-phenyl-1H-benzo[d]imidazol-2-yl)adamantane exhibits large and stable surface orientation polarization in vacuum-deposited films due to the subtle orientation selectivity of the molecule and the non-conjugated adamantane core.

Hybridization of Aminoadamantanes with Cinnamic Acid Analogues and Elucidation of Their Antioxidant Profile

A series of seventeen cinnamic acid hybrids (4ai–ci) were obtained through an amidation of aminoadamantanes (amantadine, rimantadine, and memantine) with mixed anhydride generated from different substituted cinnamic acid and ethyl chloroformate. 1H NMR, 13C NMR, IR, and HRMS were used for the confirmation of the structures of the synthesized hybrids. Moreover, the antioxidant profiles of amides were estimated as per five different in vitro methods: 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2′-azinobis-3-ethylbenzothiazoline-6-sulfonic acid cation radical (ABTS⁺), ferric reducing antioxidant power (FRAP), cupric reducing antioxidant capacity (CUPRAC) assay, and inhibition of Fe(III)/asc induced lipid peroxidation (LP) in brain homogenate. For comparison, caffeic acid (CaffA), known as a potent naturally occurring antioxidant, was used as a reference compound in our study. The results revealed that the most prominent antioxidant activity was demonstrated by compound 4b2, with excellent CUPRAC, FRAP, scavenging ABTS+˙ potential, and inhibition of Fe/asc–induced LP, followed by 4c6 > 4a6 > CaffA > 4c5 and 4a5 > 4a7. Overall, the results suggest that the hybrids (4b2, 4c6, and 4a6) consisting of a caffeoyl moiety and lipophilic adamantane core endow the molecules with the higher antioxidant activity than their parent compound (caffeic acid), especially against LP. Thus, these promising antioxidants could have beneficial effects in various pathological conditions, where oxidative stress is implicated.

Nonbonded Force Field Parameters from Minimal Basis Iterative Stockholder Partitioning of the Molecular Electron Density Improve CB7 Host-Guest Affinity Predictions.

Binding affinity prediction by means of computer simulation has been increasingly incorporated in drug discovery projects. Its wide application, however, is limited by the prediction accuracy of the free energy calculations. The main error sources are force fields used to describe molecular interactions and incomplete sampling of the configurational space. Organic host-guest systems have been used to address force field quality because they share similar interactions found in ligands and receptors, and their rigidity facilitates configurational sampling. Here, we test the binding free energy prediction accuracy for 14 guests with an aromatic or adamantane core and the CB7 host using molecular electron density derived nonbonded force field parameters. We developed a computational workflow written in Python to derive atomic charges and Lennard-Jones parameters with the Minimal Basis Iterative Stockholder method using the polarized electron density of several configurations of each guest in the bound and unbound states. The resulting nonbonded force field parameters improve binding affinity prediction, especially for guests with an adamantane core in which repulsive exchange and dispersion interactions to the host dominate.

Alkoxy-capped carbazole dendrimers as host materials for highly efficient narrowband electroluminescence by solution process

Narrowband electroluminescence from multi-resonance thermally activated delayed fluorescence (MR-TADF) emitters have attracted much attention owing to their potential in developing high-resolution organic light-emitting diode (OLED) displays. However, host materials used for MR-TADF emitters are mainly focused on small molecules that are relying on vacuum deposition for device fabrication. Here, we demonstrate the design of novel host materials with dendritic structures consisting of a non-conjugated adamantane core and four alkoxy-capped carbazole dendrons in periphery for solution-processed MR-TADF OLEDs with highly efficient narrowband electroluminescence. By introducing electron-donating n-butoxy capping groups to carbazole units and using the second-generation dendrons instead of the first-generation ones, triplet energies for the dendritic hosts are kept at higher than 2.80 eV, but the highest occupied molecular orbital (HOMO) levels can be considerably elevated from −5.51 to −5.19 eV, leading to barrier-free hole injection from anode to emissive layer. Solution-processed OLEDs based on the alkoxy-capped dendritic host and B,N-containing MR-TADF emitter reveal narrowband emission with full-width at half-maximum of 42 nm, together with low turn-on voltage of 2.8 V, maximum external quantum efficiency of 24.2% and power efficiency of 95.0 lm W−1, which represent the promising device efficiencies for narrowband electroluminescence by solution process.

Poly-phenylene jacketed tailor-made dendritic phenylazomethine ligand for nanoparticle synthesis.

Synthesizing metal clusters with a specific number of atoms on a preparative scale for studying advanced properties is still a challenge. The dendrimer templated method is powerful for synthesizing size or atomicity controlled nanoparticles. However, not all atomicity is accessible with conventional dendrimers. A new tailor-made phenylazomethine dendrimer (DPA) with a limited number of coordination sites (n = 16) and a non-coordinating large poly-phenylene shell was designed to tackle this problem. The asymmetric dendron and adamantane core four substituted dendrimer (PPDPA16) were successfully synthesized. The coordination behavior confirmed the accumulation of 16 metal Lewis acids (RhCl3, RuCl3, and SnBr2) to PPDPA16. After the reduction of the complex, low valent metal nanoparticles with controlled size were obtained. The tailor-made dendrimer is a promising approach to synthesize a variety of metal clusters with desired atomicity.

Synthesis and radical polymerization of acrylate and methacrylate bearing an isocyanurate core with adamantyl bisurethane moieties

AbstractIn this article, we report the synthesis of acrylate and methacrylate bearing an isocyanurate core with two adamantyl urethane moieties and their radical homo‐ and copolymerization with n‐butyl methacrylate (BMA). The synthesized polyacrylate exhibits higher 5% weight loss and glass transition temperatures (Td5 and Tg) than those of the comparative polyacrylate, synthesized from the isocyanurate‐based acrylate with two hexyl urethane moieties, suggesting that the rigid adamantane core incorporated in the side chains of polymer largely contributes to increase in thermal stability of polymer. Similarly, the obtained copolymers show higher Tg values than that of homopolymer derived from BMA, leading to the synthesized monomers are useful as a comonomer to enhance thermal property of polymer.

Front Cover Picture: Enantioselective Desymmetrization of 1,3‐Disubstituted Adamantane Derivatives via Rhodium‐Catalyzed C−H Bond Amination: Access to Optically Active Amino Acids Containing Adamantane Core (Adv. Synth. Catal. 6/2021)

The front cover picture illustrates that starting from the tetrahedron as a source, a road splits into two. On the left side of the road, alpha-amino acid derived from methane is passing. On the right side of the road, amino acid containing the adamantane core derived from adamantane is passing. Hoping that optically active amino acids containing the adamantane core are useful as large analogs of alpha-amino acids, their preparation by an enantioselective desymmetrization of 1,3-disubstituted adamantane derivatives via rhodium-catalyzed C–H bond amination was examined. Details can be found in the Full Paper by Risa Yasue and Kazuhiro Yoshida (R. Yasue, K. Yoshida, Adv. Synth. Catal. 2021, 363, 1662–1671; DOI: 10.1002/adsc.202001419).

Enantioselective Desymmetrization of 1,3‐Disubstituted Adamantane Derivatives via Rhodium‐Catalyzed C−H Bond Amination: Access to Optically Active Amino Acids Containing Adamantane Core

AbstractIn order to synthesize optically active amino acids containing the adamantane core, an enantioselective desymmetrization of adamantanes via rhodium‐catalyzed C−H bond amination was examined. After investigating various conditions, it was found that the coupling reaction between disubstituted adamantane and aryloxysulfonamide was catalyzed by Rh2(S‐TCPTTL)4 to furnish the desired products having up to 85% ee (e.r.=92.4: 7.6) (>99% ee after recrystallization). The synthetic utility of the enantioenriched products as chiral building blocks was demonstrated by transforming one of them into a dipeptide derivative and a Schiff‐base ligand. The absolute configuration of one of the amino acid derivatives was determined unambiguously by X‐ray single‐crystal structure analysis.magnified image

All-in-One: Sensing, Adsorptive Removal, and Photocatalytic Degradation of Nitro-Explosive Contaminants by Microporous Polycarbazole Polymer.

A highly multitasking 3D polycarbazole based microporous organic polymer (ACzMOP) is rationally prepared via a low-cost FeCl3 catalyzed polymerization route utilizing a newly developedTd-symmetric adamantane core tetracarbazolic monomer. The nitrogen-rich ACzMOP integrated with photo-redox active electron-rich π-conjugated polycarbazole modules featuring large BET surface area of 1568 m2 g-1 , pore volume of 1.58 cc g-1 , excellent physicochemical stability, and strong fluorescence in both aqueous and solid phases. Aqueous suspension including ACzMOP coated paper strip is highly responsive to the aqueous solution of nitroaromatics especially 2,4-dinitrotoluene, an unavoidable intermediate of 2,4,6-trinitrotoluene contamination, with ultra-trace level detection capability (up to 0.32 ppb). The thin layer of solid polymer is capable of detecting nitroaromatic vapors, especially nitrotoluenes in a very sensitive manner. Moreover, the polymer exhibit record uptake of nitrotoluenes and nitrophenols with maximum uptake capability up to 510mg g-1 setting a new benchmark among known porous materials. The polymer efficiently degrades toxic 4-nitrophenol to the value-added 4-aminophenol precursor (TOF = 0.143 h-1 ) via photocatalytic pathway. For the very first time, ACzMOP as a single material system is capable of efficiently sensing and removing all sorts of nitroaromatic contaminations with regenerability under mild washing/vacuumconditions.

Anti-adipogenicadamantane type polycyclic polyprenylated acylphloroglucinols from Hypericum subsessile

Hypersubones D–H (1–5), five new polycyclic polyprenylated acylphloroglucinols (PPAPs) type metabolites with intriguing adamantane and homo-adamantane skeletons, were characterized from aerial parts of Hypericum subsessile. Compounds 1–2 were elucidated to share an adamantane core with 28,29-expoxide moiety, while 3–5 were homo-adamantane type PPAPs sharing a1,2-dioxepane ring system. Their structures were determined on the basis of comprehensive NMR and MS spectroscopic data.The anti-adipogenesis activities of these isolates were evaluated through employing 3T3-L1 cells as an in vitro system using oil red O staining, and compounds 1, 2 and 5 were able to significant inhibit the adipocyte differentiation, which implied that these compounds possessed anti-adipogenic activity.

Exceptionally Stable Microporous Organic Frameworks with Rigid Building Units for Efficient Small Gas Adsorption and Separation.

Three microporous organic frameworks (hereafter denoted as MPOF-Ads) based on a rigid adamantane core have been successfully synthesized via Sonogashira-Hagihara polycondensation coupling in high yields, 83.7-94.6%. The obtained amorphous MPOF-Ads networks have high Brunauer-Emmett-Teller surface areas (up to 737.3 m2 g-1), narrow pore size distribution (0.95-1.06 nm), and superior thermal (the initial decomposition temperature T5% under an N2 atmosphere can reach 410 °C) and chemical stability (no apparent degradation in common organic solvents or strong acid/base solutions after 7 days). At 273 K and 1.0 bar, these MPOF-Ads networks present good uptake capacities for small gas molecules (13.9 wt % CO2 and 1.66 wt % CH4) for which the presence of high surface area, predominant microporosity, and narrow pore size distribution are beneficial. In addition, the as-prepared MPOF-Ads networks possess moderate isosteric heats for CO2 (Qst = 19.5-30.3 kJ mol-1) and show desired CO2/N2 and CO2/CH4 selectivity (36.3-38.4 and 4.1-4.3 based on Henry's law and 17.88-24.92 and 4.24-5.70 based on ideal adsorbed solution theory, respectively). With the demonstrated properties, the synthesized MPOF-Ads networks display potential for small gas storage and separation that can be used in harsh environments because of their superior physical and chemical stability.

Dendritic host materials with non-conjugated adamantane cores for efficient solution-processed blue thermally activated delayed fluorescence OLEDs

Dendritic hosts containing non-conjugated adamantane cores are developed for solution-processed blue TADF OLEDs with a maximum external quantum efficiency of 18.3%.

Exploring Rigid and Flexible Core Trivalent Sialosides for Influenza Virus Inhibition.

Herein, the chemical synthesis and binding analysis of functionalizable rigid and flexible core trivalent sialosides bearing oligoethylene glycol (OEG) spacers interacting with spike proteins of influenza A virus (IAV) X31 is described. Although the flexible Tris‐based trivalent sialosides achieved micromolar binding constants, a trivalent binder based on a rigid adamantane core dominated flexible tripodal compounds with micromolar binding and hemagglutination inhibition constants. Simulation studies indicated increased conformational penalties for long OEG spacers. Using a systematic approach with molecular modeling and simulations as well as biophysical analysis, these findings emphasize on the importance of the scaffold rigidity and the challenges associated with the spacer length optimization.

Electron-Transfer Properties of Phenyleneethynylene Linkers Bound to Gold via a Self-Assembled Monolayer of Molecular Tripod.

The three-point adsorption of tripod-shaped molecules enables the formation of robust self-assembled monolayers (SAMs) on solid surfaces, where the component molecules are fixed in a strictly upright orientation. In the present study, SAMs of a rigid molecular tripod consisting of an adamantane core and three CH2SH groups were employed to arrange ferrocene on a gold surface through oligo(p-phenyleneethynylene) linkers. Cyclic voltammetry of the monolayers demonstrated high surface coverage of ferrocene, yet the molecular interaction among adjacent ferrocene units was negligible. This was because of the extended intermolecular distance caused by the bulky tripod framework. The rates of electron transfer from the ferrocene to the gold surface through different linker lengths were determined by electrochemical measurements, from which the decay factor for oligo(p-phenyleneethynylene) wire was evaluated.