Our laboratory specializes in supramolecular photophysics with emphasis on fluorescent and luminescent signalling systems. We have comprehensively reviewed this entire area in Chem. Rev. 1997, 97, 1515 and updated it in Tetrahedron 2005, 61, 8551. We (along with P. Tecilla) collected 46 articles from virtually all the current leaders in this field into a Guest Editor issue (J. Mater. Chem. 2005, 15, 2637-2973). 6 other commissioned articles which missed the deadline for inclusion appeared in later issues. Various aspects of the concepts underlying our research efforts have been summarized in Chem. Soc. Rev. 1992, 21, 187; Pure Appl. Chem. 1996, 68, 1443; Analyst 1996, 121, 1759; Adv. Supramol. Chem. 1997, 4, 1; Proc. Natl. Acad. Sci. USA 1999, 96, 8336, Pure Appl. Chem. 2001, 73, 503; Chem. Commun. 2002, 2461; J. Chem. Soc. Dalton Trans. 2003, 1902. We were the first to generalize the principle of photoinduced electron transfer (PET) for the development of fluorescent sensors. We have reviewed this specific area in Top. Curr. Chem. 1993, 163, 223 and updated it in Analyst 2009, 134, 2385 and in Chem. Soc. Rev. 2015, 44, 4203. Here, a PET process is designed to occur easily between a fluoro/lumophore and a receptor which are connected via a spacer unit. Thus the fluorescence is 'switched off'. When the analyte binds to the receptor module, the PET process is seriously retarded leading to the 'switching on' of fluorescence. Since then, we have developed a range of selective sensors for several cations and other species whose fluorescence flares up upon encountering the appropriate analyte (J. Chem. Soc. Chem. Commun. 1985, 1669; ibid. 1986, 1709; ibid. 1989, 1054; ibid. 1989, 1183; ibid. 1990, 186; Chem. Commun. 1996, 1967; ibid. 1996, 2191; Tetrahedron Lett. 1990, 31, 5193; ibid. 1991, 32, 421; ibid. 1991, 32, 425; Biosensors 1989, 4, 169; Angew. Chem. Int. Ed. Engl. 1990, 29, 1173; ibid. 1995, 34, 1728; J. Chem. Soc. Perkin Trans. 2 1992, 1559; ibid. 1993, 1611; ibid. 1995, 685; ACS Symp. Ser. 1993, 538, 45; Chem. Lett. 1995, 123; NATO ASI-C Ser. 1997, 492, 143; Tetrahedron 2004, 60, 11125). New ideas in sensing, such as extending dynamic range and robotic mapping, were published in J. Am. Chem. Soc. 2007, 129, 3050 and Angew. Chem. Int. Ed. Engl. 2008, 47, 4667 respectively. Measurement of sodium ions near membranes, important in nerve signalling, was achieved in Angew. Chem. Int. Ed. 2016, 55, 768.

Perhaps our most influential work concerned the invention of molecular logic gates (Nature (London) 1993, 364, 42; J. Chem. Soc. Chem. Commun. 1994, 1213) one of which produced a world record in terms of miniaturization of a computational act (J. Am. Chem. Soc. 2005, 127, 8920). Other important breakthroughs are the construction of the first phosphorescent sensory systems (J. Chem. Soc. Chem. Commun. 1991, 1148), the first fluorescent sensors for membrane-bounded protons (J. Chem. Soc. Chem. Commun. 1994, 405), the construction of the lanthanide complexes whose luminescence spectra are ion-switchable (Angew. Chem. Int. Ed. Engl., 1996, 35, 2116; Chem. Commun., 1997, 1891), demonstration of internally referenced molecular fluorescent PET sensors (New J. Chem. 1996, 20, 871), designed 'Off-On-Off' fluorescent PET sensors/switches (Chem. Commun. 1996, 2399), ‘Off-On’ digital AND logic gate molecules suitable for binary arithmetic (J. Am. Chem. Soc. 1997, 119, 7891) and extension of the fluorescent PET sensing principle to irreversible organic reactions (Tetrahedron Lett. 1998, 39, 5077). More recent ‘firsts’ have been the emulation of aspects of the photosynthetic reaction centre (Chem. Commun. 1999, 163), demonstration of integrated molecular logic (J. Am. Chem. Soc. 1999, 121, 1393), proof-of-principle of molecular-scale arithmetic (J. Am. Chem. Soc. 2000, 122, 3965), reconfigurable and superposed molecular logic (Chem. Eur. J. 2002, 8, 4935; Chem. Commun. 2004, 2048) and direct detection of ion-pairs (Chem. Commun. 2003, 2010). The concept of a ‘Lab-on-a-Molecule’ was introduced in J. Am. Chem. Soc. 2006, 128, 4950. We introduced a self-assembly ‘plug-and-play’ approach to produce molecular logic gates in Chem. Commun. 2009, 1386. Human-level computation such as edge detection and outline drawing were introduced in J. Am. Chem. Soc. 2015, 137, 3763 and Chem. Sci. 2015, 6, 4472 respectively.

The first wide-scope application of molecular computation was presented in Nature Mater. 2006, 5, 787. This showed that combinatorial chemistry and cell diagnostics could benefit from Molecular Computational Identification (MCID) which extends the RFID (Radiofrequency Identification) approach based on semiconductor computing to smaller objects which appear in large populations. We wrote updated reviews on molecular logic and computing in Nature Nanotechnol. 2007, 2, 399 and in Chem. Commun. 2015, 51, 8403. Most importantly, my single-author monograph ‘Molecular Logic-based Computation’ of 400 pages was published by the Royal Society of Chemistry in 2013. It was rapidly translated into Chinese (Fenzi luogi jisuan, East China University of Science and Technology Press, Shanghai)) and Japanese (Bunshi ronri geto: Joho shori no dekiru kinosei bunshi, Kodansha, Tokyo) in 2014.

Fluorescent PET sensors have also been immobilized in inorganic (Tetrahedron Lett. 1996, 37, 7039) and organic (Chem. Eur. J. 1998, 4, 1810) polymer matrices. The most sensitive molecular thermometers anywhere at time of publication (Anal. Chem. 2003, 75, 5926; ibid. 2004, 76, 1793) as well as related logic gates (J. Am. Chem. Soc. 2004, 126, 3032) emerged from a collaboration with Nara Women’s University, Japan. We have also reviewed the emerging fields of photonic molecular switches for information technology and photoionic supermolecules in Chem. Ind. 1994, 19 Dec., 992 and in J. Chem. Educ. 1997, 74, 53 respectively.

Because of the relevance of our work for the monitoring of biologically important species and for molecule - based information processing, it has been supported extensively since 1987 (I arrived at Queen's in 1986) by the Science and Engineering Research Council (SERC/EPSRC) (grants GR/E/08828, GR/E/37941, GR/F/77098, GR/H/05527, GR/J/38840 totalling UK£ 400,035 (including 40% overheads)). Industrial support is also occurring at several levels from different sectors. The Department of Education of Northern Ireland (DENI) and Queen's University have also supported our work with several postgraduate studentships. NATO has also supported our collaborative research efforts with Prof. J.-P. Soumillion at Universite Catholique de Louvain. The European Community has also supported our contribution to a network on molecular-level devices and machines to the value of e176,765. They have also contributed UK£103,890 through the Programme for Peace and Reconciliation for our effort in molecular nanotechnologies. The Japan Society for the Promotion of Science has also supported a named Fellow to work in Belfast to the value of UK£101,000.

A real-life application of our research has achieved considerable commercial success. The Fluorescent PET sensor design was used as the platform of a portable diagnostic tool – a blood gas analyzer for hospital critical care units and ambulances. The specific sensors for sodium, potassium and calcium were designed, synthesized and tested in collaboration with scientists at AVL Bioscience Corporation, Roswell, GA. The product was rolled out in 1997 and has been sold by AVL, Roche Diagnostics, OSMETECH and OPTImedical in turn. The total sales of the sensor cassette is around 130M USD so far. Further information is available under ‘OPTI products’ on the following website: http://www.optimedical.com. Besides this human use, a veterinary variant has been licensed to IDEXX laboratories with total sales of 400M USD so far. Further information is available under ‘vetstat products’ on the following website: http://www.idexx.com. Besides the economic impact, the social impact of these devices extends over nearly two decades in many countries of the world.