Common Functional Groups Research Articles

Bone Targeting Nanoparticles for the Treatment of Osteoporosis.

Osteoporosis (OP) affects millions of people worldwide, especially postmenopausal women and the elderly. Although currentavailableanti-OPagents can show promise in slowing down bone resorption, most are not specifically delivered to the hard tissue, causing significant toxicity. A bone-targeted nanodrug delivery system can reduce side effects and precisely deliver drug candidates to the bone. This review focuses on the progress of bone-targeted nanoparticles in OP therapy. We enumerate the existing OP medications, types of bone-targeted nanoparticles and categorize pairs of the most common bone-targeting functional groups. Finally, we summarize the potential use of bone-targeted nanoparticles in OP treatment. Ongoing research into the development of targeted ligands and nanocarriers will continue to expand the possibilities of OP-targeted therapies into clinical application.

Chemical Kinetics for the Oxidation of Californium(III) Ions with Select Radiation-Induced Inorganic Radicals (Cl2•- and SO4•-).

Despite the availability of transuranic elements increasing in recent years, our understanding of their most basic and inherent radiation chemistry is limited and yet essential for the accurate interpretation of their physical and chemical properties. Here, we explore the transient interactions between trivalent californium ions () and select inorganic radicals arising from the radiolytic decomposition of common anions and functional group constituents, specifically the dichlorine (Cl2•-) and sulfate (SO4•-) radical anions. Chemical kinetics, as measured using integrated electron pulse radiolysis and transient absorption spectroscopy techniques, are presented for the reactions of these two oxidizing radicals with ions. The derived and ionic strength-corrected second-order rate coefficients (k) for these radiation-induced processes are k( + Cl2•-) = (8.28 ± 0.61) × 105 M-1 s-1 and k( + SO4•-) = (9.50 ± 0.43) × 108 M-1 s-1 under ambient temperature conditions (22 ± 1 °C).

Phenalenyl-ruthenium synergism for effectual catalytic transformations of primary amines to amides.

The synthesis of amides holds great promise owing to their impeccable contributions as building blocks for highly valued functional derivatives. Herein, we disclose the design, synthesis and crystal structure of a mixed-ligand ruthenium(II) complex, [Ru(η6-Cym)(O,O-PLY)Cl], (1) where Cym = 1-isopropyl-4-methyl-benzene and O,O-PLY = deprotonated form of 9-hydroxy phenalenone (HO,O-PLY). The complex catalyzes the aerobic oxidation of various primary amines (RCH2NH2) to value-added amides (RCONH2) with excellent selectivity and efficiency under relatively mild conditions with common organic functional group tolerance. Structural, electrochemical, spectroscopic, and computational studies substantiate that the synergism between the redox-active ruthenium and π-Lewis acidic PLY moieties facilitate the catalytic oxidation of amines to amides. Additionally, the isolation and characterization of key intermediates during catalysis confirm two successive dehydrogenation steps leading to nitrile, which subsequently transform to the desired amide through hydration. The present synthetic approach is also extended to substitution-dependent tuning at PLY to tune the electronic nature of 1 and to assess substituent-mediated catalytic performance. The effect of substitution at the PLY moiety (5th position) leads to structural isomers, which were further evaluated for the catalytic transformations of amine to amides under similar reaction conditions.

Accessing Tetrahydroquinaldic Amide and Homoproline Derivatives by Dearomative Difunctionalization of Heteroaromatics

AbstractThis study reports the first synthesis of tetrahydroquinaldic and tetrahydropicolinic amides using readily available quinolines and pyridines through dearomative difunctionalization and hydrolysis under transition‐metal‐ and reductant‐free conditions. The prepared amide products could be easily oxidized to the corresponding quinaldic and picolinic amides. Furthermore, the chemical reactivity of the amide group has been explored to develop convenient methods for their conversion to other common organic functional groups.

The Decay of Dispersion Interaction and Its Remarkable Effects on the Kinetics of Activation Reactions Involving Alkyl Chains.

The importance of dispersion interactions in many chemical processes is well recognized. It is known that the dispersion strength would decay with the increasing separation between the interacting groups; however, its effects on chemical reactivity have not been well understood. Here we reveal the decay law of dispersion interactions along the n-alkyl chain, its effective interaction ranges for common functional groups, and their remarkable effects on the kinetics of activation reactions involving alkyl chains. This is achieved by DLPNO-CCSD(T) calculations and the local energy decomposition analysis and is supported by experimental findings. In particular, our calculations indicate that the lifetime of alkyl-substituted cis-azobenzenes increases with the alkyl chain length but reaches a steady value when alkyl chains are longer than butyl groups, which is in satisfactory accordance with experimental measurements. We also propose a concise expression to describe the dispersion decay, which shows excellent agreement with our computed results.

Strategies for the Preparation of Chitosan Derivatives for Antimicrobial, Drug Delivery, and Agricultural Applications: A Review.

Chitosan has received much attention for its role in designing and developing novel derivatives as well as its applications across a broad spectrum of biological and physiological activities, owing to its desirable characteristics such as being biodegradable, being a biopolymer, and its overall eco-friendliness. The main objective of this review is to explore the recent chemical modifications of chitosan that have been achieved through various synthetic methods. These chitosan derivatives are categorized based on their synthetic pathways or the presence of common functional groups, which include alkylated, acylated, Schiff base, quaternary ammonia, guanidine, and heterocyclic rings. We have also described the recent applications of chitosan and its derivatives, along with nanomaterials, their mechanisms, and prospective challenges, especially in areas such as antimicrobial activities, targeted drug delivery for various diseases, and plant agricultural domains. The accumulation of these recent findings has the potential to offer insight not only into innovative approaches for the preparation of chitosan derivatives but also into their diverse applications. These insights may spark novel ideas for drug development or drug carriers, particularly in the antimicrobial, medicinal, and plant agricultural fields.

Prodrug Rewards in Medicinal Chemistry: An Advance and Challenges Approach for Drug Designing.

This article emphasizes the importance of prodrugs and their diverse spectrum of effects in the field of developing novel drugs for a variety of biological applications. For the purpose of illustrating the usefulness of the prodrug approach, this review covers examples of prodrugs that have been made available or are now undergoing human trials. Additionally, it included lists of the most common functional groups, carrier linkage, and reactive chemicals that can be used to create prodrugs.The primary chemical carriers employed in the creation of prodrugs, such as esters, amides, imides, NH-acidic carriers, amines, alcohols, carbonyl, carboxylic, and azo linkage, are also discussed. This review also discusses glycosidic and triglyceride mutually activated prodrugs, which aim to deliver the drugs after bioconversion at the intended site of action. The article also discusses the extensive chemistry and wide variety of applications of recently approved prodrugs, such as antibacterial, anti-inflammatory, cardiovascular, antiplatelet, antihypertensive, atherosclerotic, and antiviral, etc. In order to illustrate the prodrug and mutual drugs concept's various applications and highlight its many triumphs in overcoming the formulation and delivery of problematic pharmaceuticals, this work represents a thorough guide that includes the synthetic moiety to the reader.

Toward De Novo Catalyst Discovery: Fast Identification of New Catalyst Candidates for Alcohol‐Mediated Morita–Baylis–Hillman Reactions**

AbstractRecently we have demonstrated how a genetic algorithm (GA) starting from random tertiary amines can be used to discover a new and efficient catalyst for the alcohol‐mediated Morita–Baylis–Hillman (MBH) reaction. In particular, the discovered catalyst was shown experimentally to be eight times more active than DABCO, commonly used to catalyze the MBH reaction. This represents a breakthrough in using generative models for catalyst optimization. However, the GA procedure, and hence discovery, relied on two important pieces of information; 1) the knowledge that tertiary amines catalyze the reaction and 2) the mechanism and reaction profile for the catalyzed reaction, in particular the transition state structure of the rate‐determining step. Thus, truly de novo catalyst discovery must include these steps. Here we present such a method for discovering catalyst candidates for a specific reaction while simultaneously proposing a mechanism for the catalyzed reaction. We show that tertiary amines and phosphines are potential catalysts for the MBH reaction by screening 11 molecular templates representing common functional groups. The method relies on an automated reaction discovery workflow using meta‐dynamics calculations. Combining this method for catalyst candidate discovery with our GA‐based catalyst optimization method results in an algorithm for truly de novo catalyst discovery.

Toward De Novo Catalyst Discovery: Fast Identification of New Catalyst Candidates for Alcohol-Mediated Morita-Baylis-Hillman Reactions.

Recently we have demonstrated how a genetic algorithm (GA) starting from random tertiary amines can be used to discover a new and efficient catalyst for the alcohol-mediated Morita-Baylis-Hillman (MBH) reaction. In particular, the discovered catalyst was shown experimentally to be eight times more active than DABCO, commonly used to catalyze the MBH reaction. This represents a breakthrough in using generative models for catalyst optimization. However, the GA procedure, and hence discovery, relied on two important pieces of information; 1) the knowledge that tertiary amines catalyze the reaction and 2) the mechanism and reaction profile for the catalyzed reaction, in particular the transition state structure of the rate-determining step. Thus, truly de novo catalyst discovery must include these steps. Here we present such a method for discovering catalyst candidates for a specific reaction while simultaneously proposing a mechanism for the catalyzed reaction. We show that tertiary amines and phosphines are potential catalysts for the MBH reaction by screening 11 molecular templates representing common functional groups. The method relies on an automated reaction discovery workflow using meta-dynamics calculations. Combining this method for catalyst candidate discovery with our GA-based catalyst optimization method results in an algorithm for truly de novo catalyst discovery.

Unveiling the versatility of novel oxacalix[4]arene platform: Systematic screening and comparative study on biological and antioxidant potency

Calixarene, a third generation supramolecule, have made their signature in biomedical applications through their unique physicochemical characteristics. Oxacalixarene, a class of heteracalixarene, is less explored in this respect though it has manifested its potentiality in earlier very few reports. Here we are reporting for the first time a systematic and comparative study of biological activities of different oxacalix[4]arene(OC) systems. For this purpose, very common functional groups that are available in biomacromolecules like phenolic OH (DHOC), amine (DNOC), ester (DEOC) and amide (DAOC) have been considered for functionalization to basic OC platform and the newly synthesized compounds are characterized with state-of-the-art spectroscopic techniques. Analysis of DNA cleavage, DNA binding, cell cytotoxicity and antioxidant activity studies nicely define the diversity of OC in DNA protection or DNA damage phenomena. DHOC is able to protect oxidative cleavage of DNA up to 47 % against Fenton reagents. The order of binding constant (∼105) is observed in the following order: DHOC (phenolic OH) > DNOC (amine) > DAOC (amide). The article also reports the antioxidant activity of oxacalix[4]arene compounds for the first time, observed by DPPH inhibition assay. All the compounds possess antioxidant activities. Among those, DHOC shows maximum antioxidant activity, comparable to standard antioxidant ascorbic acid at 100 µM (DPPH: 60 µM). Indeed, the observed structure-function relationship of OC systems can be tailored in the future to design molecules that are specifically targeted for biomedical applications.

Characterized Functional Groups of Temperature- and Salt-Resistant Copolymers and Surfactants and Their Relationships.

As the physical properties of newly discovered oil and gas reservoirs become more complex and the requirements for field development effectiveness continue to increase, the performance of polymers and surfactants, which are commonly used as chemical agents in oil field development, is facing great challenges. The determinations of temperature and salt resistance of anti-temperature and anti-salt viscosity-enhancing copolymers and low-interfacial-tension surfactants in recent years have been reviewed. The mechanism of temperature and salt resistance of distinct functional groups was discussed, and the common functional groups of temperature- and salt-resistant viscosity-increasing copolymers and temperature- and salt-resistant low-interfacial-tension surfactants were pointed out. An outlook on the molecular structure design of a new temperature- and salt-resistant oil displacement agent is presented.

Native plant diversity for ecological reclamation in Moroccan open-pit phosphate mines.

Mining activities have significant impacts on the environment, particularly in terms of the destruction of natural habitats andbiodiversity loss. With the increasing awareness of the importance of ecological restoration and conservation, there is a growing need to study and understand the flora that thrives in mining sites in order to facilitate successful reclamation efforts. This study aimed to investigate the floristic composition and plant diversity of four phosphate mine sites (PMSs) in Morocco, namely Bou Craa mine (BCM), Ben Guerir mine (BGM), Youssoufia mine (YSM), and Khouribga mine (KHM). The study found a total of 215 vascular plant species from 166 genera and 49 taxonomic families across the four sites. BGM was the most diverse site with 120 plant species, followed by KHM with 75, YSM with 57, and BCM with 54. Compositae family species were the most common at BGM and KHM, while Amaranthaceae species were dominant at BCM, and Poaceae and Compositae at YSM. Therophytes (annual species) were the most common functional group (45.0%), followed by chamaephytes (19.6%) and hemicryptophytes (15.9%). Atriplexnummularia and Chenopodiumalbum were the most common species found at all four sites, while Atriplexsemibaccata, Bassiamuricata, Haloxylonscoparium, and 12 other species were common at three sites. However, 156 plant species were found at only one site. The findings of this study highlight the significant abundance of plant species in Moroccan PMSs and provide a basis for successful ecological engineering rehabilitation plans. The study emphasizes the importance of studying the indigenous plant species that naturally populate these marginal lands to ensure successful reclamation efforts.

An efficient 2-(2-Pyridyl)imidazole based copper catalyst for N-Arylation of N-heterocycles

An earth-abundant copper based 2-(2-pyridyl)imidazole (L) complex of the type [CuL2(NO3)](NO3), (1) has been characterized spectroscopically, structurally and electrochemically. The copper(II) in 1 is present in a distorted trigonal-bipyramidal coordination environment and has structural similarity with the well-known 1,10-phenanthroline (L′) coordinated copper catalytic system used in Ullmann-type N-arylation reactions. Complex 1 is more electronically rich than the corresponding 1,10-phenanthroline-based complex, [CuL′2(NO3)](NO3), (2) and shows excellent catalytic activity towards N-arylation of nitrogen heterocycles like pyrazole, imidazole, benzimidazole and less reactive indole with aryl-iodides and -bromides. Electronically deficient aryl-chlorides are also successful as a coupling agent for N-arylation with good yields. Wide spectrums of common organic functional groups are also tolerated in our catalytic conditions. A possible mechanistic route for this N-arylation reaction has been proposed by considering several experimental and spectroscopic results along with computational details.

Enantioselective Catalysis by the Umpolung of Conjugate Acceptors Involving N-Heterocyclic Carbene or Organophosphine 1,4-Addition

ConspectusConjugate acceptors are one of the most common electrophilic functional groups in organic synthesis. While useful in a diverse range of transformations, their applications are largely dominated by the reactions from which their name is derived (i.e., as an acceptor of nucleophiles in the conjugate position). In 2014, we commenced studies focused on their ability to undergo polarity inversion through the conjugate addition of Lewis base catalysts. The first step in this process provides an enolate, from which the well-developed Rauhut-Currier (RC) and Morita-Baylis-Hillman (MBH) reactions can occur; however, tautomerization to provide a species in which the β-carbon of the conjugate acceptor can now act as a donor is also possible. When we commenced studies on this topic, reaction designs with this type of species, particularly when accessed using N-heterocyclic carbenes (NHCs), had been reported on only a handful of occasions. Despite a lack of development, conceptually it was felt that reactions taking advantage of polarity switching by Lewis base conjugate addition have a number of desirable features. Perhaps the most significant is the potential to reimagine a ubiquitous functional group as an entirely new synthon, namely, a donor to electrophiles from the conjugate position.Our work has focused on catalysis with both simple conjugate acceptors and also those embedded within more complicated substrates; the latter has allowed a series of cycloisomerizations and annulation reactions to be achieved. In most cases, the reactions have been possible using enantioenriched chiral NHCs or organophosphines as the Lewis base catalysts thereby delivering enantioselective approaches to novel cyclic molecules. While related chemistry can be accessed with either family of catalyst, in all cases reactions have been designed to take advantage of one or the other. In addition, a fine balance exists between reactions that exploit the initially formed enolate and those that involve the polarity-inverted β-anion. In our studies, this balance is addressed through substrate design, although catalyst control may also be possible. We consider the chemistry discussed in this Account to be in its infancy. Significant challenges remain to be addressed before our broad aim of discovering a universal approach to the polarity inversion of all conjugate acceptors can be achieved. These challenges broadly relate to chemoselectivity with substrates bearing multiple electrophilic functionalities, reliance upon the use of conjugate acceptors, and catalyst efficiency. To address these challenges, advances in catalyst design and catalyst cooperativity are likely required.

N-Heterocyclic carbene-catalyzed remote C(sp3)–H acylation of amides

An N-heterocyclic carbene catalyzed benzylic C–H acylation of o-alkyl benzamides and cascade cyclization is developed through a radical-mediated 1,5-hydrogen atom transfer (HAT) mechanism. Different from photoredox catalysis, this light-free approach enables the generation of amidyl radicals through single-electron transfer (SET) with Breslow enolates. The mild process tolerates most common functional groups and delivers a variety of dihydroisoquinolinones in moderate to high yields. The electrochemical character of the aryloxyamide is consistent with the hypothesis of ground-state SET and a plausible mechanism for the organocatalytic transformation is proposed.

A Unified Approach to Mono- and 2,3-Disubstituted N–H Indoles

AbstractA unified approach to mono- and disubstituted N–H indoles is described by means of oxidative cyclization of 2-alkenyl anilines, which are prepared by cross-coupling of the corresponding o-bromoanilines. This procedure is operationally expedient and tolerant of common functional groups to allow regiospecific installation of the alkyl and aryl substituents.

Secondary pollinators contribute to reproductive success of a pink-flowered sand verbena population.

Secondary pollinators contribute to reproductive success of a pink-flowered sand verbena population.

Implant surface physicochemistry affects keratinocyte hemidesmosome formation.

Previous studies have shown hydrophilic/hydrophobic implant surfaces stimulate/hinder osseointegration. An analogous concept was applied here using common biological functional groups on a model surface to promote oral keratinocytes (OKs) proliferation and hemidesmosomes (HD) to extend implant lifespans through increased soft tissue attachment. However, it is unclear what physicochemistry stimulates HDs. Thus, common biological functional groups (NH2 , OH, and CH3 ) were functionalized on glass using silanization. Non-functionalized plasma-cleaned glass and H silanization were controls. Surface modifications were confirmed with X-ray photoelectron spectroscopy and water contact angle. The amount of bovine serum albumin (BSA) and fibrinogen, and BSA thickness, were assessed to understand how adsorbed protein properties were influenced by physicochemistry and may influence HDs. OKs proliferation was measured, and HDs were quantified with immunofluorescence for collagen XVII and integrin β4. Plasma-cleaned surfaces were the most hydrophilic group overall, while CH3 was the most hydrophobic and OH was the most hydrophilic among functionalized groups. Modification with the OH chemical group showed the highest OKs proliferation and HD expression. The OKs response on OH surfaces appeared to not correlate to the amount or thickness of adsorbed model proteins. These results reveal relevant surface physicochemical features to favor HDs and improve implant soft tissue attachment.

Radiolytic degradation of dodecane substituted with common energetic functional groups.

Explosives exist in and are expected to withstand a variety of harsh environments up to and including ionizing radiation, though little is known about the chemical consequences of exposing explosives to an ionizing radiation field. This study focused on the radiation-induced chemical changes to a variety of common energetic functional groups by utilizing a consistent molecular backbone. Dodecane was substituted with azide, nitro, nitrate ester, and nitramine functional groups and γ-irradiated with 60Co in order to study how the functional group degraded along with what the relative stability to ionizing radiation was. Chemical changes were assessed using a combination of analysis techniques including: nuclear magnetic resonance (NMR) spectroscopy, gas chromatography of both the condensed and gas phases, Raman spectroscopy, and Fourier transform infrared (FTIR) spectroscopy. Results revealed that much of the damage to the molecules was on the energetic functional group and often concentrated on the trigger linkage, also known as the weakest bond in the molecule. The general trend from most to least susceptible to radiolytic damage was found to be D-ONO2 → D-N3 → D-NHNO2 → D-NO2. These results also appear to be in line with the relative stability of these functional groups to things such as photolysis, thermolysis, and explosive insults.

Metal-free reductive desulfurization of C-sp3-substituted thiols using phosphite catalysis.

Phosphines and phosphites are critical tools for non-metal desulfurative methodologies due to the strength of the P[double bond, length as m-dash]S bond. An overarching premise in these methods has been that stoichiometric (or excess) P(iii) reagent is required for reactivity. Despite decades of research, a desulfurative process that is catalytic in phosphine/phosphite has not been reported. Here, we report the successful merging of two thermal radical processes: the desulfurization of unactivated and activated alkyl thiols and the reduction of P(v) = S to P(iii) by reaction with a silyl radical species. We employ catalytic trimethyl phosphite, catalytic azo-bis(cyclohexyl)nitrile, and two equivalents of tris(trimethylsilyl)silane as the stoichiometric reductant and sulfur atom scavenger. This method is tolerant of common organic functional groups and affords products in good to excellent yields.