The COST Chemistry Action D14 was conceived with the aim to increase the fundamental understanding of the chemistry of functional molecular materials. The work programme of this Action entailed the combined efforts of chemists and physicists interested in developing and evaluating novel molecularly based systems that order in two or three dimensions, and as a result of this order, exhibit novel properties. It was the aim of this Action to develop novel functional molecular and supramolecular systems, to understand the forces driving their formation and higher organisation, to develop methods to investigate, address, and manipulate these systems and, finally, to exploit their specific properties in new ‘smart materials’. In everyday life, we are using materials usually without thinking of their origin, manufacturing or structure. Materials are so important for mankind that we even name periods of human history according to them: there was a stone, bronze and iron age. What kind of materials do we need for the present, so called, information age? Of course, semiconductors, which are the backbone of modern electronics. However, as electronic components become even smaller and more densely packed, we will approach physical limits of the semiconductor technology. Molecules, molecular assemblies or nanoparticles are suitable candidates for technologies of the future. Development of functional molecules requires highly interdisciplinary research at frontiers of chemistry, physics and, in part, biology. It is not enough to design and synthesize new molecules and explore their physical properties. Careful organization of functional molecules in 2 or 3 dimensions into genuine molecular materials is crucial to achieve the desired behaviour. In fact, some functions emerge only from higher molecular organization. All these aspects were addressed by COST Action D14, which involved 62 research teams from 20 COST countries, that is ca. 180 European scientists. New functional molecules were made and studied by advanced physical techniques, building up the enabling knowledge for rational development of molecular materials. Higher organization of active molecular units has produced, for example, materials whose conductivity can be controlled magnetically, or special liquid crystals, composed of banana-shaped molecules, for electroptical applications. Very interesting functional molecules were developed in one of the D14 Working Groups, which can probe the 3-dimensional arrangement of biomolecules, such as DNA or oligopeptides. A special ruthenium complex is used, whose light-emission depends strongly on the immediate molecular environment, reporting thus on the secondary structure of investigated biomolecules. Photonics is another promising technology, which encompasses, for example, optical imaging, recording or holography. Collaborative research carried out within D14 produced special molecules which can absorb two photons of light at once. Under irradiation, they induce spatially precise polymerization and create well-defined 3D microstructures. This technique was developed for optical recording and for making optical waveguides, a photonic analogy to wires known from electronics. Efficient light-energy conversion is one of the biggest challenges and a great opportunity to our civilization. Every second, the Sun delivers to the Earth more energy then we can ever use, if only we knew how to harness it economically. One of the D14 Working Groups has worked exactly on this problem, developing new hybrid molecular-semiconductor systems to convert solar energy to electrical energy. The D14 research has thus advanced the field of photoelectrochemical devices for solar energy conversion by improving their three main components: the semiconducting films of titania, the molecular sensitizers and the electrolyte. These examples are but a few of the scientific accomplishments of the collaborations that flourished under the COST D14 umbrella. Development of new molecules and nanoparticles with special physical properties and organizing them into functional materials already produce useful devices and underlie new technologies which address imminent and arising societal needs, while new functional molecular systems exhibiting novel types of behaviour emerge. Research on molecular materials thus ventures toward yet unexpected applications and technologies, making us ready to meet the challenges to come.
