19^th European Organic Chemistry Congress November 06-07, 2023 London, UK

Biography:

Prof. Dr. Liang-An Chen received his Ph.D. with Prof. Eric Meggers at Xiamen University in 2014. He began postdoctoral research with Prof. James Leighton at Columbia University (2015-2018), then joined Indiana University (Bloomington) as a postdoctoral fellow with Prof. Kevin Brown (2018-2019), and started his independent academic career at Nanjing Normal University as a professor of chemistry (7/2019). His research interest focuses on transition metal catalysis, synthetic methodology, and asymmetric catalysis.

Abstract:

Transition metal-catalyzed cross-coupling reactions involving organometallic reagents have emerged as a practical technical for intruding saturated carbon skeleton into organic molecules. However, the cross-coupling often suffered from the use of preprepared organometallic reagents with additional tedious synthetic steps, which are often sensitive to water and air, thus requiring exceptional caution for preservation. Stoichiometric organometallic reagents are often required for the cross-coupling reaction, thus resulting in poor atom economy. To the best of our knowledge, most coupling reactions employed C(sp2)- or C(sp)-metal reagents. By contrast, the method for accessing alkyl metal species (C(sp3)-M) is still a significant challenge; furthermore, they are prone to undergo β-H elimination or homolytic cleavage. Therefore, harnessing C(sp3)-M for transition metal-catalyzed coupling reaction represents a daunting challenge. Herein, we will report our recent contribution to transition-metal catalyzed cross-coupling reactions using in situ generated catalytic C(sp3)-M as a key intermediate, featuring high step- and atom-economy.

Biography:

Dilip K. Maiti was born September 09, 1970, in West Bengal, India. He received his B. Sc. in chemistry in 1991 and M. Sc. (organic chemistry major) in 1993, from University of Calcutta, India. He achieved his Ph. D. on stereoselective synthesis, from Indian Institute of Chemical Biology in 1998. He had done his postdoctoral research in the School of Medicine, Wayne State University, USA. In 2005, he joined as a Reader faculty at University of Calcutta and became full Professor in 2011. Currently he is serving as the Vice-Chancellor of Biswa Bangla University. His major research activity is focused on organic synthesis, catalysis and fabrication of smart organic nanomaterials, sensors and devices.

Abstract:

The area of nanoscience and nanotechnology has grown tremendously over the past two decades and is expected to expand rapidly in the near future. Organic nanomaterials have several advantages over inorganic counterpart. Organic nanomaterial-products are lighter, more flexible, biodegradable, ease for fabricating devices, less expensive, non-magnetic and easily be purified. Semiconducting, electronic and optoelectronic properties can easily be modified through  changing size, shape, chemical structure, morphology and installation of a wide range of functional groups, which in turn generates innovative semiconducting, conducting, photoluminescence, storage, display and sensing performances to achieve highly efficient devices. Consequently, organic nanomaterials open up the door to many exciting and advanced new applications that would be impossible using inorganic materials. Thus, design and synthesis of new organic compounds, their fabricated unidirectional materials and development of new electronic property are desirable for achieving organic electronics-based high-tech devices of ultimate sensitivity and day-to-day usable innovative component. We have developed organic nanofibrils as a sensing device for lethal gaseous phosgene, detecting health pollutant cyanide in water, luminescent material for inkless writing and self-erasing application, nanofiber-based materials for crossbar devices to achieve organic resistive random access memory (RRAM) and write-once-read-many-times (WORM) memory devices for non-editable database, archival memory, electronic voting, and radio frequency identification (RFID) applications.

Biography:

Abstract:

The diarylamine functionality is widespread in natural products and other bioactive species,^1,2 and as a result a range of synthetic methods has been developed for its preparation. We have demonstrated that diaryliodonium salts are not only selective precursors to fluoroarenes³ but that these materials are also suitable arylating agents for a range of anilines.
Although successful, this process required elevated temperatures (130 °C) and extended reaction times (24h) limiting its application. We now wish to report translation of this methodology to a continuous process (Uniqsis FlowSyn⁵) which has addressed these restrictions.

Initial optimization of diphenylamine production was achieved by investigation of concentration, temperature, flow-rate and choice of counter-ion. As Ullmann-type conditions have been employed in arylation reactions⁶ we also investigated the effect of using a copper coil as the reactor in addition to the more usual stainless steel, PTFE coils (Fig. 1). It was found that the copper coil/trifluoroacetate counter-ion combination was essential to conduct the reaction at room temperature with a residence time of only 80 min. The process was suitable for a range of anilines e.g. R = 3,4-(OMe)₂ (87%, Fig. 2); 4-NO₂ (70%); 2,4,6-Me₃ (80%); 1-naphthylamine (68%) and a range of diaryliodonium salts

Biography:

Khushal Siddiq was born in Samangan Province of Afghanistan in 1999, and migrated to England, Liverpool in 2009 and then to London in 2010 to attend secondary school. He graduated from University College London (UCL) in 2021 with a master’s degree in Organic Chemistry: Drug Discovery. Then he moved to Queen Mary University of London (QMUL) in 2022 to pursue a PhD in Organic Chemistry, currently working on extending the scope of ‘Metal-Free Aryne-Mediated Cross Dehydrogenative Coupling’ supervised by Dr Christopher R. Jones at the School of Physical and Chemical Sciences (SPCS).

Abstract:

Arynes are neutral but extremely versatile, unstable, and reactive intermediates that have experienced a recent resurgence in interest due to the development of precursors that act under mild conditions, with the most prominent being 2-(trimethylsilyl)aryl triflates also known as Kobayashi’s aryne precursor. The distinctive reactivity of arynes enables the construction of complex polycyclic and heterocyclic aromatic frameworks in short order which has captivated the interest of organic chemists. Direct functionalization of otherwise chemically inert C(sp3)-H bonds provides a potent strategic approach for the synthesis of complex molecules by removing the need for pre- functionalisation of the coupling partners. This in turn reduces the number of synthetic steps involved in the synthetic route. Over the last decade, Cross dehydrogenative coupling (CDC) has emerged as a powerful tool for the selective construction of C-C bonds, from simple and abundant C-H bonds via tandem oxidation. However, some challenges remain to be solved. For instance, an external driving force in the form of a transition metal catalyst and/or sacrificial oxidant is required to overcome the unfavorable thermodynamics associated with forming a C-C bond and the accompanying loss of hydrogen (H2).
By exploiting the reactivity of transient aryne intermediates, a metal- free, redox-neutral approach to C(sp3)-C(sp3/sp2/sp) coupling via an intramolecular 1,5-hydride transfer onto an aryne intermediate has been developed. Mechanistic studies have provided support for a zwitterion intermediate which activates a pronucleophile. Subsequent recombination yields the α-C-H functionalized amines. A diverse range of pronucleophiles have been demonstrated to be amenable to this new approach to CDC reactions which utilizes aryne intermediates. Preliminary work has shown that the scope can be extended beyond C- C coupling with a number of examples of phosphites undergoing the cross dehydrogenative coupling with tetrahydroisoquinoline derivatives, furnishing α-aminophosphonates.
 

Biography:

The electrochemical processes in two dimensional (2D) materials have a serious impact on their properties encompassing their structural integrity and electronic structure. However, it is difficult to discriminate the roles of the basal plane, edges, defects, or interlayer space in the complex interplay between the material’s properties and the electrochemistry. Also, the electrochemical response at the electrode/electrolyte and the effect of ions at the interface cannot be monitored precisely. The common methods do not allow for simple access to the particular area of a sample, and thus, the spatial resolution is low and there is no distinction between the role of the individual constituents.

Here we show that in-situ Raman microspectroscopy combined with electrochemical analysis provides a powerful method for gaining simultaneous information on the structure and electronic properties of the electrochemically gated 2D material in concentrated aqueous electrolytes. This technique enabled us to discriminate the localized charge transfer process between an electrolyte and graphene in the defect enrich domain within the localized area of 10-20 µm². The defects were produced within a graphene monolayer using an oxygen plasma by changing the exposure time from 0-30 sec. The localized in-situ spectroelectrochemical studies enabled us to monitor the gradual change in graphene doping in the samples for different time exposures to oxygen plasma. The charge transfer was found to occur between the electrolyte and graphene through the defects at the covalently bonded oxygen functional groups. The study provides important knowledge of the local interfacial structure and electrostatic gating at a potentiostatically controlled electrode material, which is of fundamental and technological importance for many electrochemical, chemical and industrial applications.

Abstract:

The electrochemical processes in two dimensional (2D) materials have a serious impact on their properties encompassing their structural integrity and electronic structure. However, it is difficult to discriminate the roles of the basal plane, edges, defects, or interlayer space in the complex interplay between the material’s properties and the electrochemistry. Also, the electrochemical response at the electrode/electrolyte and the effect of ions at the interface cannot be monitored precisely. The common methods do not allow for simple access to the particular area of a sample, and thus, the spatial resolution is low and there is no distinction between the role of the individual constituents.

Here we show that in-situ Raman microspectroscopy combined with electrochemical analysis provides a powerful method for gaining simultaneous information on the structure and electronic properties of the electrochemically gated 2D material in concentrated aqueous electrolytes. This technique enabled us to discriminate the localized charge transfer process between an electrolyte and graphene in the defect enrich domain within the localized area of 10-20 µm². The defects were produced within a graphene monolayer using an oxygen plasma by changing the exposure time from 0-30 sec. The localized in-situ spectroelectrochemical studies enabled us to monitor the gradual change in graphene doping in the samples for different time exposures to oxygen plasma. The charge transfer was found to occur between the electrolyte and graphene through the defects at the covalently bonded oxygen functional groups. The study provides important knowledge of the local interfacial structure and electrostatic gating at a potentiostatically controlled electrode material, which is of fundamental and technological importance for many electrochemical, chemical and industrial applications.