Liangliang Cai

Tongji University · Department of Material Science and Engineering

Elimination reactions are one of the most important reactions in organic synthesis, especially in the formation of alkenes and alkynes. Herein, based on scanning tunneling microscopy, we report the bottom-up synthesis of one-dimensional carbyne-like nanostructures, metalated carbyne ribbons with the incorporation of Cu or Ag atoms, through α- and β...

During the last decades, the bottom–up strategy of on-surface molecular reactions has been extensively investigated in order to fulfill controllable fabrication of covalent interlinking nanostructures/nanomaterials at atomic scale. A variety of organic reactions have been introduced to substrates, such as Ullmann coupling, Glaser coupling, cyclodeh...

The structural transformation from symmetric cumulene to broken-symmetry polyyne within a one-dimensional (1-D) atomic carbon chain is a signature of Peierls distortion. Direct observation of such a structural transformation with single-bond resolution is, however, still challenging. Herein, we design a molecule with cumulene moiety (Br2C=C=C=CBr2)...

Ullmann coupling of 4,4’’-dibromo-p-terphenyl (DBTP) thermally catalyzed on Ag(111) surface was studied by scanning tunneling microscopy. Detailed experimental measurement shows that the Ullmann coupling reaction pathways of DBTP molecules can be controlled by pre-self-assembly, and the dissymmetric dehalogenation reaction is realized. Moreover, se...

From an interplay of high-resolution UHV-STM imaging and DFT calculations, we have achieved on-surface synthesis of graphyne nanowires through stepwise reactions involving two different types of dehalogenative homocoupling reactions (i.e.,...

Intramolecular dehalogenation reaction as an essential step is generally involved in the deprotection of carbon-carbon double bonds in solution chemistry. However, harsh reaction conditions often limit the functional-group compatibility and cause the selectivity problems. In comparison with traditional solution reactions, on-surface chemical reacti...

Polyacetylene (PA) comprises one-dimensional chains of sp²-hybridized carbon atoms that may take a cis or trans configuration. Owing to its simple chemical structure and exceptional electronic properties, PA is an ideal system to understand the nature of charge transport in conducting polymers. Here, we report the on-surface synthesis of both cis-...

Stereoselective synthesis of geometrically pure isomers is challenging and important in a variety of chemistry related disciplines and applications. The recently developed on‐surface synthesis strategy provides us opportunities in the fabrication of specific nanostructures which remain challenging by conventional solution chemistry. In this work, w...

Conductive polymers are of great importance in a variety of chemistry related disciplines and applications. The recently developed bottom-up on-surface synthesis strategy provides us with opportunities in the bottom-up fabrication of various nanostructures in a flexible and facile manner, which could be investigated by high-resolution microscopic t...

Surface-assisted synthesis involving hydrocarbons has aroused great attention due to its remarkable potential in constructing novel carbon nanostructures. Particularly, C–C coupling between reactants by cleaving the pre-defined C–X groups (X stands for hydrogen and halogens) followed by forming new carbon-carbon bonds, represents one of the best ch...

On-surface synthesis shows significant potential in constructing novel nanostructures/nanomaterials, which has been intensely studied over the recent years. The formation of acetylenic scaffoldings provides an important route to the fabrication of emerging carbon nanostructures including carbyne, graphyne and graphdiyne, which involve the chemicall...

On-surface synthesis shows significant potential in constructing novel nanostructures/nanomaterials, which has been intensely studied over the recent years. The formation of acetylenic scaffoldings provides an important route to the fabrication of emerging carbon nanostructures including carbyne, graphyne and graphdiyne, which involve the chemicall...

The on-surface activation of carbon-halogen groups represents an efficient route to produce radicals for constructing various hydrocarbons and carbon nanostructures. To our knowledge, the so far employed halide precursors have only one halogen attached to a carbon atom. It is thus of particular interest to study the effect of attaching more than on...

The on-surface activation of carbon-halogen groups represents an efficient route to produce radicals for constructing various hydrocarbons and carbon nanostructures. To our knowledge, the so far employed halide precursors have only one halogen attached to a carbon atom. It is thus of particular interest to study the effect of attaching more than on...

We studied the self-assembly of melem on the Au(111) and Ag(111) surface. By scanning tunneling microscopy imaging, we have observed two different STM appearances of the melem molecule within the self-assembled nanostructure on Au(111), which are resulted from the different intermolecular bonding configurations. Moreover, further DFT details includ...

Through high-resolution UHV-STM imaging and DFT calculations, we find that a di-carbonitrile molecule unexpectedly prefers to form a hydrogen-bonded nanostructure rather than coordination bonded ones on both Cu(110) and Cu(100) at room temperature. These findings highlight the importance of the surface symmetry and molecule–surface interactions in...

On-surface C-C coupling reactions of molecular precursors with alkynyl functional groups demonstrate great potential for the controllable fabrication of low-dimensional novel carbon nanostructures/nanomaterials like carbyne, graphyne and graphdiyne which demand the in-corporation of highly active sp-hybridized carbons. Recently, through a dehydroge...

We have successfully achieved the stereoselective synthesis of a specific cis-diene moiety through a dehalogenative homocoupling of alkenyl bromides on the Cu(110) surface, where the formation of a cis-form organometallic intermediate is the key to such a stereoselectivity as determined by DFT calculations.

Due to stability issues, carbyne, a one-dimensional chain of carbon atoms, has been much less investigated than other recent carbon allotropes such as graphene. Beyond that, metalation of such a linear carbon nanostructure with regularly distributed metal atoms is even more challenging. Here, through an on-surface synthesis approach, we report a su...

The construction of nanostructures through covalent interlinking of molecular building blocks on metal surfaces is among the most active subjects in surface science community. Various chemical reactions have been employed on surfaces. Especially, on-surface synthesis involving hydrocarbons has aroused particular attention due to the interest of fab...

Fractals are ubiquitous in nature as in the forms of snowflakes, clouds, lighting, leaves and trees, etc. The formation of fractals is of utmost interest to artists and scientists. Efforts in forming molecular fractals have mainly been devoted in synthetic chemistry, and few concentrations have been focused on surfaces albeit the rapid development...

On-surface self-assembly from molecular building blocks directed by supramolecular interactions has been widely reckoned as an efficient method for controllable construction of low-dimensional nanostructures and nanomaterials. Numerous efforts have been devoted to exploring the self-assembled behaviors of molecular precursors on different surfaces...

Template cations have been extensively employed in the formation, stabilization and regulation of structural polymorphism of G-quadruplex structures in vitro. However, the direct addition of salts onto solid surfaces, especially under ultra-high-vacuum (UHV) conditions, to explore the feasibility and universality of the formation of G-quartet compl...

On-surface formation of two-dimensional supramolecular network structures using molecular self-assembly has been an efficient and the most widely employed method. Through delicate modifying the molecular candidates with specific substituents, it is possible to build on-surface nanostructures according to one’s will. Here, from the interplay of high...

Homocouplings of hydrocarbon groups including alkynyl (sp1), alkyl (sp3), and aryl (sp2) have recently been investigated on surfaces with the interest of fabricating novel carbon nanostructures/nanomaterials and getting fundamental understanding. Investigated herein is the on-surface homocoupling of an alkenyl group which is the last elementary uni...

Homocouplings of hydrocarbon groups including alkynyl (sp(1) ), alkyl (sp(3) ), and aryl (sp(2) ) have recently been investigated on surfaces with the interest of fabricating novel carbon nanostructures/nanomaterials and getting fundamental understanding. Investigated herein is the on-surface homocoupling of an alkenyl group which is the last eleme...

Wurtz reactions feature the dehalogenated coupling of alkyl halides. In comparison to their widely investigated counterparts, Ullmann reactions, Wurtz reactions have however been scarcely explored on surfaces. Herein, by combining high-resolution STM imaging and DFT calculations, we have systematically investigated Wurtz reactions on three chemical...

Two-dimensional (2D) polymers, which are covalently interlinked molecular sheets extended in two dimensions, have received considerable attention because of their unique and appealing properties. Vast efforts have been devoted to the synthesis of covalently interlinked 2D polymers from molecular precursors via bottom-up fabrication in surface scien...

Although the G-quartet structure has been extensively investigated due to its biological importance, the formation mechanism, in particular, the necessity of metal centers, of an isolated G-quartet on solid surfaces remains ambiguous. Here, by using scanning tunneling microscopy under well-controlled ultra-high-vacuum conditions and density functio...

The construction of ordered on-surface nanostructures from molecular self-assembly has attracted wide attention due to their potential applications in nanoscience and nanotechnology. To date, main efforts have been concentrated on delicately functionalizing the molecular precursors with certain functional groups to induce specific intermolecular in...

Low temperature (100 °C) solidification of clay brick waste has been achieved by use of NaOH solution after addition of calcium hydroxide. Flexural strength was approximately 26 MPa for specimens containing 30 % (m/m) calcium hydroxide which had been treated with 3 M NaOH then solidified for 48 h. The development of strength of the specimens was fo...