Dicyano- and tetracyanopentacene: foundation of an intriguing new class of easy-to-synthesize organic semiconductors

Glöcklhofer, F.; Petritz, A.; Karner, E.; Bojdys, M. J.; Stadlober, B.; Fröhlich, J.; Unterlass, M. M. Journal of Materials Chemistry C 2017, Advance Article, DOI: 10.1039/C7TC00143F.

Cyanated pentacenes are very promising candidate materials for ambipolar and n-type transistors. However, only a few examples have been obtained to date – all requiring lengthy, multi-step processes. Herein, we present the first preparation of 5,7,12,14-tetracyanopentacene (TCP) and a facile, scaled-up preparation of 6,13-dicyanopentacene (DCP). Both compounds are prepared by a one-pot synthesis using cheap quinones as starting materials. Detailed crystallographic investigations evince that the bulk assemblies of both cyanated pentacenes are dominated by non-covalent interactions, resulting in a dense, stable, face-to-face packing and in an intriguing packing motif for TCP. Very low frontier molecular orbital energy levels and a reversible bleaching of TCP are revealed by cyclic voltammetry. Finally, both cyanated pentacenes are used in proof-of-concept organic thin-film transistors (OTFTs) operating under ambient conditions. This work highlights the potential of cyanation for larger acenes and presents a straightforward route to the rational design of this promising class of materials.

DOI: 10.1039/C7TC00143F

CUCAM Workshop

 

 

 

 

 

 

Want to find out more about the new “Charles University Center of Advanced Materials” (CUCAM)? Come along on the 8th of February to our kick-off workshop at Charles University, Department of Chemistry, Hlavova 8 in Prague!

 

Carbon nitride frameworks and dense crystalline polymorphs

Pickard, C. J.; Salamat, A.; Bojdys, M. J.; Needs, R. J.; McMillan, P. F. Physical Review B 2016, 94, 094104, DOI: 10.1103/PhysRevB.94.094104, arXiv:1605.02893.

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We used ab initio random structure searching (AIRSS) to investigate polymorphism in C3N4 carbon nitride as a function of pressure. Our calculations reveal new framework structures, including a particularly stable chiral polymorph of space group P43212 containing mixed sp2 and sp3-bonding, that we have produced experimentally and recovered to ambient conditions. As pressure is increased a sequence of structures with fully sp3-bonded C atoms and three-fold coordinated N atoms is predicted, culminating in a dense Pnma phase above 250 GPa. Beyond 650 GPa we find that C3N4 becomes unstable to decomposition into diamond and pyrite-structured CN2.

DOI: 10.1103/PhysRevB.94.094104, arXiv:1605.02893

WO2016027042 (A1) – Two-dimensional carbon nitride material and method of preparation

Cooper, A. I. and Bojdys, M. J. (2016). Two-dimensional carbon nitride material and method of preparation. WO2016027042 (A1).

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Graphitic carbon nitride has been prepared and its structure confirmed by extensive characterization. This material has useful electronic, in particular semiconducting, properties. Crystalline thin films have been prepared. Synthesis may be carried out by condensation of unsaturated carbon- and nitrogen- containing compound(s) in inert solvent such as a salt melt, forming graphitic carbon nitride at a gas-liquid or solid-liquid interface.

External Links: Patentscope, Espacenet, Google Patents

“2D Materials – Beyond Silicone and Graphene” – by Mara Staffilani

Michael J. Bojdys, head of the Functional Nanomaterials group at the Charles University in Prague, describes a class of [graphene-]analogous, two-dimensional sheets made from a mix of carbon and nitrogen that are here to complement the one property that the wonder material graphene has not: a useful electronic band gap.” – Dr Mara Staffilani

MaterialsViews 2016. [Link]

macp.201500312

Highlight for the article: Bojdys,* M. J. Macromolecular Chemistry and Physics 2016, 217, 232–241. [DOI: 10.1002/macp.201500312]

Design Strategies in Hydrothermal Polymerization of Polyimides

Baumgartner, B.; Bojdys, M. J.; Skrinjar, P.; Unterlass,* M. M. Macromolecular Chemistry and Physics 2015, DOI: 10.1002/macp.201500287.

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Hydrothermal polymerization, a benign synthesis for aromatic polyimides, is studied in detail to gain greater insight in the ongoing mechanisms. By performing an extensive set of experiments at various parameters, polyimides of outstanding crystallinity are obtained and could thus refine their crystal structure from powder XRD data. Initial condensation intermediates could isolate, which indicates that HTP is mechanistically closely related to classical step-growth polycondensations.

DOI: 10.1002/macp.201500287

This is the pre-peer reviewed version of the following article: Baumgartner, B.; Bojdys, M. J.; Skrinjar, P.; Unterlass,* M. M. Macromolecular Chemistry and Physics 2015, DOI: 10.1002/macp.201500287, which has been published in final form at [DOI: 10.1002/macp.201500287].

2D or not 2D-layered functional (C, N) materials “beyond silicon and graphene”

Bojdys,* M. J. Macromolecular Chemistry and Physics 2015, DOI: 10.1002/macp.201500312.

TOC

As of 2015, the number of mobile phone subscriptions outstrips Earth’s human population. Critical raw materials (CRMs) and silicon, won in energy intensive refinement make up the electronics in all these devices. While graphene still has to deliver on its potential in electronic applications, we look to 2D polymer materials that go beyond silicon and graphene.

DOI: 10.1002/macp.201500312

This is the pre-peer reviewed version of the following article: Bojdys,* M. J. Macromolecular Chemistry and Physics 2015, DOI: 10.1002/macp.201500312, which has been published in final form at [DOI: 10.1002/macp.201500312].

Dr. Michael J. Bojdys receives ERC Starting Grant

LOGO-ERC

For the second time in recent years the European Research Council (ERC) has awarded one of the prestigious ERC Starting Grants to a scientist of the Department of Organic Chemistry at the Charles University in Prague. Materials chemist Dr. Michael J. Bojdys received this grant endowed with up to 1.5 Million Euro to promote basic research on “functional nanomaterials beyond graphene” over the next five years. Function and structure of these organic materials beyond graphene can provide opportunities for designing new generations of electronic devices such as field-effect transistors, gas sensors etc.

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Bojdys Group