The dark side of hydrogen bonds in the design of optical materials: a charge-density perspective.
A combined investigation of the structural, electronic, and optical properties of three crystalline nonaaqualanthanoid(III) triflates, [Ln(H2 O)9 (CF3 SO3 )3 ], has provided unambiguous experimental evidence for charge redistribution in the first coordination sphere of a lanthanide ion as a result of hydrogen bonds with outer-sphere anions. As well as resulting in charge transfer from the noncoordinated anions to the coordinated water molecules, these hydrogen bonds give rise to a new excited state, an hydrogen-bond-induced charge-transfer state, which is observed experimentally for the first time. This state was shown to be responsible for the previously unknown negative aspect of hydrogen bonds with a lanthanide-bound water molecule: rather than increasing the luminescence efficiency of the complex, they can lead to additional quenching that is unfavorable for the task-specific design of optical materials.
A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, 119991, Vavilova Str., 28, Moscow (Russia). unelya@xrlab.ineos.ac.ru.
Yulia V
YV
Nelyubina
Lada N
LN
Puntus
Konstantin A
KA
Lyssenko
X-ray diffraction; charge-density redistribution; lanthanides; luminescence quenching; topological analysis