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Author: Semih Durmus Publisher: ISBN: Category : Anti-infective agents Languages : en Pages : 193
Book Description
"The introduction of N-heterocyclic carbenes (NHCs) to organometallic and inorganic chemistry was achieved by the synthesis and isolation of chromium and mercury NHC complexes by Öfele and Wanzlick in 1968. The synthesis and characterization of numerous carbene metal complexes by Lappert et al were a significant contribution to this area of chemistry. NHCs have become an important area of research after the isolation of the first stable carbene by Arduengo in 1991. In chapter 1, the synthesis and biological activities of NHCs and their silver(I) and gold(I) derivatives are discussed. In chapter 2, the synthesis and characterization of an imidazolium-linked cyclophane is discussed as well as its potential use as a medicinal agent. In chapter 3, the synthesis and characterization of a silver(I) NHC complex is reported. The antimicrobial activity of the silver(I) NHC complex is also reported against clinically important bacteria. In chapter 4, the synthesis of a variety of silver(I) NHC complexes and their carbene transfer reactions to gold(I) reagents are reported. The gold(I) NHC complexes are also investigated for their anticancer properties. In chapter 5, the use of urocanic acid as NHC precursor is reported. The synthesis and characterization of the first silver(I) NHC complex derived from biological molecule urocanic acid is discussed as well as its antimicrobial activity."--Abstract.
Author: Semih Durmus Publisher: ISBN: Category : Anti-infective agents Languages : en Pages : 193
Book Description
"The introduction of N-heterocyclic carbenes (NHCs) to organometallic and inorganic chemistry was achieved by the synthesis and isolation of chromium and mercury NHC complexes by Öfele and Wanzlick in 1968. The synthesis and characterization of numerous carbene metal complexes by Lappert et al were a significant contribution to this area of chemistry. NHCs have become an important area of research after the isolation of the first stable carbene by Arduengo in 1991. In chapter 1, the synthesis and biological activities of NHCs and their silver(I) and gold(I) derivatives are discussed. In chapter 2, the synthesis and characterization of an imidazolium-linked cyclophane is discussed as well as its potential use as a medicinal agent. In chapter 3, the synthesis and characterization of a silver(I) NHC complex is reported. The antimicrobial activity of the silver(I) NHC complex is also reported against clinically important bacteria. In chapter 4, the synthesis of a variety of silver(I) NHC complexes and their carbene transfer reactions to gold(I) reagents are reported. The gold(I) NHC complexes are also investigated for their anticancer properties. In chapter 5, the use of urocanic acid as NHC precursor is reported. The synthesis and characterization of the first silver(I) NHC complex derived from biological molecule urocanic acid is discussed as well as its antimicrobial activity."--Abstract.
Author: Han Vinh Huynh Publisher: John Wiley & Sons ISBN: 1118698800 Category : Science Languages : en Pages : 352
Book Description
The Organometallic Chemistry of N-heterocyclic Carbenes describes various aspects of N-heterocyclic Carbenes (NHCs) and their transition metal complexes at an entry level suitable for advanced undergraduate students and above. The book starts with a historical overview on the quest for carbenes and their complexes. Subsequently, unique properties, reactivities and nomenclature of the four classical NHCs derived from imidazoline, imidazole, benzimidazole and 1,2,4-triazole are elaborated. General and historically relevant synthetic aspects for NHCs, their precursors and complexes are then explained. The book continues with coverage on the preparation and characteristics of selected NHC complexes containing the most common metals in this area, i.e. Ni, Pd, Pt, Ag, Cu, Au, Ru, Rh and Ir. The book concludes with an overview and outlook on the development of various non-classical NHCs beyond the four classical types. Topics covered include: Stabilization, dimerization and decomposition of NHCs Stereoelectronic properties of NHCs and their evaluation Diversity of NHCs Isomers of NHC complexes and their identification NMR spectroscopic signatures of NHC complexes normal, abnormal and mesoionic NHCs The Organometallic Chemistry of N-heterocyclic Carbenes is an essential resource for all students and researchers interested in this increasingly important and popular field of research.
Author: Olaf Kühl Publisher: John Wiley & Sons ISBN: 0470685840 Category : Science Languages : en Pages : 364
Book Description
N-heterocyclic carbenes (NHCs) have found increasing use as reagents for a range of organic transformations and in asymmetric organocatalysis. The performance of these molecules can be improved and tuned by functionalisation. Functionalised carbenes can anchor free carbenes to the metal site, introduce hemilability, provide a means to immobilise transition metal carbene catalysts, introduce chirality, provide a chelate ligand or bridge two metal centres. NHC can be attached to carbohydrates and campher, derived from amino acids and purines, they can be used as organocatalysts mimicking vitamin B1 or as weak “solvent” donors in lanthanide chemistry. Functionalised N-Heterocyclic Carbene Complexes describes major trends in functionalised NHC ligands, aiming to assist readers in their attempts to develop and apply their own functionalised carbenes. After an introduction to the chemistry and behaviour of NHC, the book gives a detailed description of functionalised carbenes and their complexes according to a range of functional groups, each with a discussion of the synthetic route, structure, stability and performance. Functionalised N-Heterocyclic Carbene Complexes is an essential guide to fine-tuning this important class of compounds for practitioners, researchers and advanced students working in synthetic organometallic and organic chemistry and catalysis.
Author: James Laurence Hickey Publisher: ISBN: Category : Anti-infective agents Languages : en Pages : 311
Book Description
This work focuses on the design and synthesis of Au(I) and Ag(I) complexes from ligand systems that aim to combine both N-heterocyclic carbene (NHC) and phosphine ligand types. A number of synthetic approaches towards both the ligands and the prepared metal complexes have been developed, with a concerted effort on achieving the desired Au(I) or Ag(I) complexes with minimal reaction steps and synthetic style. The thesis body is divided into two main sections. The first section addresses the preparation of suitable ligand precursors of potential Au(I) and Ag(I) complexes in the form of halo- and phosphino-functionalised imidazolium salts. Several series of haloalkylimidazolium salts were prepared that encompass a range of halogens (Cl, Br, I), alkyl substituents (Me, i-Pr, t-Bu, n-Bu), differing alkyl linker length (n = 0-3), and a variety of organic spacers employed to bridge multi-imidazolium moieties. Novel bidentate and multidentate phosphinoalkylimidazolium salts were synthesised from the various haloalkylimidazolium salts, via the substitution of a halide with nucleophilic diphenylphosphide. A new approach towards rare methylene bridged phosphinomethylimidazolium salts was achieved from the reactions of halomethylimidazolium salts with diphenylphosphine. The second section investigates the preparation of Au(I) and Ag(I) complexes from the halo- and phosphino-functionalised imidazolium salts. A series of dicationic 10, 12, and 14-membered metallacyclic Ag(I) complexes were prepared from the bidentate phosphinoalkylimidazolium salts. The dinuclear Ag(I) metallacycles combine two phosphino-functionalised NHC ligands that are bridged by two coordinated Ag(I) ions in an exclusively head-to-head arrangement. A dinuclear Ag(I) metallacycle was investigated for transmetallation potential to a Au(I) complex and found to selectively transmetallate at the Ag(I) coordinated to the NHC ligands to form a bimetallic metallacycle. Unexpected phosphine oxidation of a 10-membered dinuclear Ag(I) metallacycle resulted in complex disproportionation to an isolable and rare silver(I) trimer. Metal-NHC complexes from haloalkylimidazolium salts have not been reported previously, a novel approach to the synthesis of a series of Au(I) complexes from haloalkylimidazolium salts and a respective gold source was developed and is reported herein. Different synthetic approaches towards Au(I) complexes with the phosphinoalkylimidazolium salts explored a variety of ways to generate the NHC from an imidazolium in the presence of the phosphine. A one-pot, high yielding synthesis of a dinuclear Au(I) complex from PPh3 was also devised, with controlled assembly of the complex resulting in a similar head-to-head ligand arrangement to the dinuclear Ag(I) metallacycles. As an aside, a family of mononuclear [Au(R2NHC)2]+ complexes (R = Me, i-Pr, t- Bu, n-Bu, Cy) prepared previously in our research group, was expanded because of the promising antimitochondrial activity shown by [Au(i-Pr2NHC)2]+. Two new [Au(R2NHC)2]+ complexes with simple alkyl chain functionality were prepared with fine-tuned lipophilicity in close proximity to that of [Au(i-Pr2NHC)2]+.
Author: Silvia Diez-Gonzalez Publisher: Royal Society of Chemistry ISBN: 1782626816 Category : Science Languages : en Pages : 637
Book Description
In less than 20 years N-heterocyclic carbenes (NHCs) have become well-established ancillary ligands for the preparation of transition metal-based catalysts. This is mainly due to the fact that NHCs tend to bind strongly to metal centres, avoiding the need of excess ligand in catalytic reactions. Also, NHC‒metal complexes are often insensitive to air and moisture, and have proven remarkably resistant to oxidation. This book showcases the wide variety of applications of NHCs in different chemistry fields beyond being simple phosphine mimics. This second edition has been updated throughout, and now includes a new chapter on NHC‒main group element complexes. It covers the synthesis of NHC ligands and their corresponding metal complexes, as well as their bonding and stereoelectronic properties and applications in catalysis. This is complemented by related topics such as organocatalysis and biologically active complexes. Written for organic and inorganic chemists, this book is ideal for postgraduates, researchers and industrialists.
Author: Tammy J. Siciliano Publisher: ISBN: Category : Anti-infective agents Languages : en Pages : 266
Book Description
The synthesis of the first metal N-heterocyclic carbene (NHC) complexes by Öfele and Wanzlick started an exciting new class of coordination chemistry. The isolation of the first free carbene by Arduengo provided a novel route from which numerous NHC metal complexes have been made. Among their many applications, the potential for therapeutic use has been an area of growing interest and a topic of this review. The first gold NHC complex synthesized from its silver NHC precursor by Lin revolutionized the frontier for simple gold NHC generation to which this review is rooted. Chapter 1 provides a review on past and current routes by which gold(I) and gold(III) NHC complexes have been synthesized. The discussion focuses on their structural comparisons and a detailed history of the medicinal use of gold is presented before exploring their current role in the field. In Chapter 2, the stability of gold-(bis)NHC complexes in aqueous and physiological solution is discussed in comparison to their silver-(bis)NHC precursors. Silver has been used as an antimicrobial agent for thousands of years and the antimicrobial properties of both are explored. Chapter 3 focuses further on water stability and antimicrobial properties as it is applied to silver acetate NHC complexes in comparison to silver- and gold-(bis)NHC analogues. Imidazolium salts, NHC precursors, have been shown to possess antimicrobial properties. Chapter 4 investigates these properties on synthesized imidazolium salts with a variety of functional groups on varying positions of the imidazole ring. There are several different types of silver dressings commercially available. Chapter 5 evaluates the antimicrobial effectiveness of eight such dressings and comparisons are made.
Author: Steven P. Nolan Publisher: John Wiley & Sons ISBN: 9783527314003 Category : Science Languages : en Pages : 330
Book Description
This first handbook to focus solely on the application of N-heterocyclic carbenes in synthesis covers metathesis, organocatalysis, oxidation and asymmetric reactions, along with experimental procedures. Written by leading international experts this is a valuable and practical source for every organic chemist.
Author: Steven P. Nolan Publisher: John Wiley & Sons ISBN: 3527671242 Category : Science Languages : en Pages : 690
Book Description
This comprehensive reference and handbook covers in depth all major aspects of the use of N-heterocyclic carbene-complexes in organic synthesis: from the theoretical background to characterization, and from cross-coupling reactions to olefin metathesis. Edited by a leader and experienced scientist in the field of homogeneous catalysis and use of NHCs, this is an essential tool for every academic and industrial synthetic chemist.
Author: Brian D. Wright Publisher: ISBN: Category : Anti-infective agents Languages : en Pages : 310
Book Description
Since the discovery of the first stable silver N-heterocyclic carbene complex by Arduengo in 1991, the field of silver N-heterocyclic carbene complexes has expanded greatly. These complexes have been studied extensively for use in catalysis, as transmetallation agents, and more recently for pharmaceutical applications. Silver has been used for centuries as an anti-microbial agent, and more recently has been shown to have anti-tumor activity as well. Combination with the easily modified N-heterocyclic carbene ligand yields a drug that can be rationally designed for increased water solubility, increased lipophilicity, or to increase activity. These complexes have shown great results, and will be the main focus of this dissertation. Chapter 1 of this dissertation reviews silver N-heterocyclic carbene complexes as promising antimicrobial agents and the evolution of the field over the past two decades. Chapter 2 discusses the synthesis of a new N-heterocyclic carbene backbone, 4,5,6,7-tetrachlorobenzimidazole, and the corresponding silver complexes for antimicrobial use. These complexes were then examined in vitro against a panel of clinical bacteria, displaying inhibitory concentrations between 0.25-4 [micrograms]/mL. Additionally, two of the silver complexes displayed antimicrobial activity against a silver-resistant E. coli strain. Chapter 3 discusses the rational design of several new naphthalene containing imidazolium cations, the precursors to silver N-heterocyclic carbene complexes, for the use as anti-tumor drugs. These new imidazolium cations have been designed to increase water solubility, anti-tumor activity, and encapsulation efficiency into biodegradable delivery devices through modification of the substituents. These cations have demonstrated in vitro anti-tumor activity comparable to cisplatin against three types of lung cancer. The anti-tumor activity increased with the increase in the length of the alkyl chain substituent. Additionally, it was noted that the position of the alkyl chain on the naphthalene rings did not affect the anti-tumor activity of the cations. Chapter 4 discusses the in vitro anti-tumor activity of silver carbene complexes based on selected imidazolium cations from chapter 3. These complexes have demonstrated an increase in water solubility in comparison to previously reported silver N-heterocyclic carbene anti-tumor complexes. Additionally, the complexes have displayed anti-tumor activity at clinically relevant levels, demonstrating IC50 values ranging from 5-25 [micrograms]/mL. In general, the anti-tumor activity increased as the length of the alkyl chain on the ligand increased. The highest activity was displayed by SCC44, which unlike the other complexes contained two naphthalene rings.
Author: Semih Durmus
Author: Semih Durmus
Author: Han Vinh Huynh
Author: Olaf Kühl
Author: James Laurence Hickey
Author: Silvia Diez-Gonzalez
Author: Wukun Liu
Author: Tammy J. Siciliano
Author: Steven P. Nolan
Author: Steven P. Nolan
Author: Brian D. Wright