1) Light harvesting using inorganic coordination complexes as dyes in dye-sensitized solar cells (DSCs)


We are focusing on the development of dyes (sensitizers) for attachment to n-type semiconductors (usually TiO2) for incorporation into DSCs. The now well-established Grätzel-type DSCs use ruthenium(II)-containing dyes, and our research thrust is the development of dyes that contain first row d-block metals (e.g. copper, zinc) which are Earth abundant. The major challenge is to increase the sunlight-to-electrical-power conversion efficiencies of the dyes.

For an overview of this area:
The emergence of copper(I)-based dye sensitized solar cells
C. E. Housecroft and E. C. Constable
Chem. Soc. Rev., 2015, 44, 8386-8398. doi.org/10.1039/C5CS00215J

The versatile SALSAC approach to heteroleptic copper(I) dye assembly in dye-sensitized solar cells
F. J. Malzner, C.E. Housecroft and E.C. Constable
Inorganics, 2018, 6, 57. doi.org/10.3390/inorganics6020057

2) Development of emissive complexes for application in light-emitting electrochemical cells (LECs)

Tuning the photoluminescence (PL) properties of iridium(III) complexes of the type [Ir(N^N)(C^N)2]+ where N^N is a chelating ligand such as a 2,2'-bipyridine derivative and C^N is a cyclometalling chelate, can be achieved by careful selection and combination of the ligands. Colour tuning is one goal; another is extending the lifetimes and increasing the quantum yields of the emissions. For applications in light-emitting electrochemical cells, we must also investigate the electroluminescent properties under device configuration - this work is carried out in collaboration with the research groups of Dr Henk Bolink and Professor Enrique Ortí (University of Valencia).

For insight into this area:
Over the LEC rainbow: colour and stability tuning of cyclometallated iridium(III) complexes in light-emitting electrochemical cells
C. E. Housecroft and E.C. Constable
Coord. Chem.  Rev., 2017, 350, 155–177. doi.org/10.1016/j.ccr.2017.06.016

[Cu(P^P)(N^N)][PF6] compounds with bis(phosphane) and 6-alkoxy, 6-alkylthio, 6-phenyloxy and 6-phenylthio-substituted 2,2'-bipyridine ligands for light-emitting electrochemical cells
M. Alkan-Zambada, S. Keller, L. Martínez-Sarti, A. Prescimone, J.M. Junquera-Hernández, E.C. Constable, H.J. Bolink, M. Sessolo, E. Ortí and C.E. Housecroft
J. Mater. Chem. C, 2018, 6, 8460-8471. doi.org/10.1039/C8TC02882F

Phosphane tuning in heteroleptic [Cu(N^N)(P^P)]+ complexes for light-emitting electrochemical cells
F. Brunner, A. Babaei, A. Pertegás, J. M. Junquera-Hernández, A. Prescimone, E. C. Constable, H. J. Bolink, M. Sessolo, E. Ortí and C. E. Housecroft
Dalton Trans., 2019, 48, 446-460. doi.org/10.1039/c8dt03827a

3) Water splitting and water oxidation catalysts

Water splitting is the conversion of liquid water to H2 and O2 using visible light energy. Nature achieves this by photosynthesis, and in biological processes, a highly organized phospholipid membrane is crucially important. One of our on-going areas of research is the development of water splitting (to form H2 and O2 from H2O) or water oxidation (looking only at one half of the water splitting process) catalysts. One approach is to use Langmuir-Blodgett (LB) films to transfer ordered monolayers of both a polyoxometallate cluster and the bis- or tris(bipyridine) ruthenium(II) photosensitizer onto a conducting substrate for use in a water splitting device.

For relevant work:
Bis(4'-(4-pyridyl)-2,2':6',2"-terpyridine)ruthenium(II) complexes and their N-alkylated derivatives in catalytic light-driven water oxidation
H. Lv, J. A. Rudd, P. F. Zhuk, J. Y. Lee, E. C. Constable, C. E. Housecroft, C. L. Hill, D. G. Musaev and Y. V. Geletii
RSC Advances, 2013, 3, 20647-20654.

Assembling model tris(bipyridine)ruthenium(II) photosensitizers into ordered monolayers in the presence of the polyoxometallate anion [Co 4(H2O)2 (α-PW9O34)2]10-
N. S. Murray, J. A. Rudd, A.-C. Chamayou, E. C. Constable, C. E. Housecroft, M. Neuburger and J. A. Zampese
RSC Advances, 2014, 4, 11766-11775.

4) Functional coordination polymers and networks


The combination of transition metal-based building blocks with polypyridyl ligands such as 4,2':6',4''-terpyridine is a powerful strategy for the assembly of 1D-, 2D and 3D polymers and networks. Gaining control over the assembly processes is challenging. Ligand backbones may be functionalized with, for example, photoactive domains. Our interests in these systems are both understanding their structural characteristics (challenging crystallography) and developing functionalized systems that can act as, e.g. sensors or host materials.

For overviews of our recent work, see:
Divergent 4,2′:6′,4′′- and 3,2′:6′,3′′-terpyridines as linkers in 2- and 3-dimensional architectures
C. E. Housecroft, CrystEngComm, 2015, 17, 7461-7468. doi.org/10.1039/C5CE01364J

Tetratopic bis(4,2':6',4''-terpyridine) and bis(3,2':6',3''-terpyridine) ligands as 4-connecting nodes in 2D-coordination networks and 3D-frameworks
E.C. Constable and C. E. Housecroft
J. Inorg. Organomet. Polym. Mater., 2018, 28, 414-427. doi.org/10.1007/s10904-017-0671-0

Ditopic and tetratopic 4,2':6',4"-Terpyridines as Structural Motifs in 2D- and 3D-Coordination Assemblies
C. E. Housecroft and E.C. Constable
, 2019, 73, 462-467. doi.org/10.2533/chimia.2019.462