A green photoluminescent triruthenium cluster (1) has been chemisorbed on highly luminescent porous silicon (Psi) layers, either freshly prepared or chemically modified with I-decene, ethyl undecylenate, or undecylenic acid, in order to study the influence of the cluster on the photoluminescence (PL) arising from the Psi. Immersing the hydrogen-terminated Psi in a hexane solution of (1) for several days at room temperature led to the quenching of PL arising from Psi; the only PL detected was due to the Ru cluster (1). A complete quenching of the PL due to Psi was also observed when derivatized Psi surfaces were exposed to the same solution of (1); in these cases, the PL of (1) also shifted to lower energies. Both the quenching of the PL arising from the Psi layers and the shift in the PL of the cluster (1) are likely due to the difference in the chemical interaction of the PO moiety and the CO groups of the Ru cluster with the terminal functional group of the organic monolayer. (C) 2003 Elsevier Science B.V. All rights reserved.