Now in its third year, the Green and Sustainable Chemistry Conference has become an established tradition. Each year the conference addresses a broad range of topics related to Green and Sustainable Chemistry in parallel sessions. The conference (held during 13–16 May 2018, in Berlin) aimed to provide a forum for participants from academia and industry, from authorities and other institutions, to address these challenges in a broad unique manner across the diverse fields of Green and Sustainable Chemistry.

The main new feature in 2018 was the start-up session, which was very well received and will therefore be part of the conference in 2019 again (Dresden, Germany, 5–8 May). A specific feature of this conference is its importance in transferring academic findings into practice: it is not enough to discuss it is also necessary to act. This session is also the consequent next step to the workshop for young entrepreneurs which we have at the beginning of the conference each year. Yet another way this conference is unique in bringing together high-level science and stake holders in the field.

Professor Michael Graetzel, the conference's opening speaker, gave a very good insight into past, present, and future of photovoltaic cells. He pioneered investigations of electron transfer reactions in mesoscopic systems and their application in electricity and fuel generation from sunlight and electricity storage in lithium batteries. He invented the dye-sensitized solar cell that in turn engendered perovskite photovoltaics, the most exciting breakthrough in the recent history of photovoltaics. This set the tone for the high level of expertise presented by the invited speakers for each session. The articles in this issue are contributed by invited speakers and are based on their lectures at the conference. They give a small taste of the range of topics covered by this conference and the breadth of the themes that it covered. The conference report in this issue (https://www.sciencedirect.com/science/article/pii/S2452223618301378) provides more details and our sister journal Sustainable Chemistry and Pharmacy will publish some of the papers presented at the Conference.

The diversity of the topics covered by the conference is well illustrated by the papers in this selection. To begin, chemical weapons: not a subject that comes readily to mind when thinking of green chemistry, but this topic nicely demonstrates the interplay of green and sustainable chemistry. Many would like to make sure that these chemical weapons were never used but how can you dispose of them safely? Jonathan Forman's paper looks into the role of green and sustainable chemistry in chemical disarmament and nonproliferation, a thought-provoking topic.

Photocatalysis is a topic more associated with sustainability and green chemistry. Alexandre Gellé and Audrey Moores’ paper on plasmonic nanoparticles looks into their use as light-driven catalysts (https://www.sciencedirect.com/science/article/pii/S2452223618300701).

Nanomaterials are also proving to be useful catalysts. Maurizio Selva and Rafael Luque look into the ways advances in nanomaterials design and engineering will maximize the use of resources (https://www.sciencedirect.com/science/article/pii/S2452223618300737).

The pharmaceutical industry saves many lives but at what cost to the environment? One of the greatest problems with pharmaceuticals is removing them and their waste products from the aquatic environment. Benoit Roig and coworkers’ paper looks at some of the many ways the risk to the environment can be reduced. Along the life cycle of a pharmaceutical there are many opportunities for improvement. These include: the better use of resources, improving synthesis and production methods, developing more biodegradable drugs, and reducing the number of medications prescribed (https://www.sciencedirect.com/science/article/pii/S2452223618300671). Sustainable production methods are also discussed in the paper by Peter Fantke and Nicole Illner on producing consumer products in a sustainable manner (https://www.sciencedirect.com/science/article/pii/S2452223618300737).

The articles in this special issue demonstrate the broad scope of the conference as well as that of Current Opinion in Green and Sustainable Chemistry and why there is a difference between green and sustainable chemistry. Taking so many factors into account is a challenge: chemists need to develop a different way of thinking. However, making chemistry both green and sustainable provides a lot of opportunities for chemists as well. There is still much to discuss and develop, which is why the 4th Green and Sustainable Chemistry Conference (https://www.elsevier.com/events/conferences/green-and-sustainable-chemistry-conference) will again provide an inspiring environment for discussion at a very high scientific level.