We investigate waveguide efficiency of CsPbI3 microwire waveguides and their photodegradation over a range of continuous wave laser excitation energies and intensities. Under modest laser input intensities <1 kW cm−2 we observe a wavelength dependent efficiency of light propagation in the waveguides. At increased power densities and wavelengths of 473 nm or shorter, microwires undergo photoablation into discrete fragments. Use of diffraction-limited excitation allowed localised cleavage of the microwires with observation of transient photoluminescence from degradation products. TEM analysis of the microwires revealed transformation from the yellow δ-phase to amorphous phases in the region of the photodamage with a degraded morphology consistent with efficient thermal transfer and induced melting.

The novel cyaphide complex trans-[Ru(dppe)2Me(CP)] is obtained in excellent yields and exhibits the first instance of con-trolled reactivity of any terminal-cyaphide complex. Its treatment with ZnX2 / PPh3 effects selective metathesis of the methyl moiety to afford the unprecedented halo-cyaphide complexes trans-[Ru(dppe)2(X)(CP)] (X = Cl, Br, I), which are structurally characterized (X = Cl, Br). Exemplified with the trans-bromide, these compounds are susceptible to substitution of the halides by nucleophilic reagents – illustrated with Me2Mg – and also readily undergo halide abstraction by TlOTf to afford the first hypo-coordinate cyaphide complex, viz. [Ru(dppe)2(CP)].OTf, which is isolable in bulk and exhibits good stability. NMR spectroscopic and crystallographic data reveal the latter to adopt a square pyramidal geometry with an accessible coordinate vacancy, which is susceptible to the addition of nucleophiles. This is illustrated analytically by reactions with Me2Mg and LiCCPh, and with its facile bulk carbonylation to afford trans-[Ru(dppe)2(CO)(CP)]+.

The reaction of the bis(pentalene)dititanium complex Ti2(μ:η5,η5-Pn†)2 (Pn† = C8H4(1,4-SiiPr3)2) (1) with the N-heterocyclic carbene 1,3,4,5-tetramethylimidazol-2-ylidene results in intramolecular C–H acti- vation of an isopropyl substituent to form a tucked-in hydride (3). Whilst pyridine will also effect this cyclometallation reaction to form (5), the pyridine analogue of (3), the bases 1,2,4,5-tetramethyl-imid- azole, 2,6-lutidine, DABCO or trimethylphosphine are ineffective. The reaction of (1) with 2,6-dichloro- pyridine affords crystallographically characterised (6) which is the product of oxidative addition of one of the C–Cl bonds in 2,6-dichloro-pyridine across the Ti–Ti double bond in (1). The tucked-in hydride (3) reacts with hydrogen to afford a dihydride complex (4) in which the tuck-in process has been reversed; detailed experimental and computational studies on this reaction using D2, HD or H2/D2 support a mechanism for the formation of (4) which does not involve σ-bond metathesis of H2 with the tucked-in C–H bond in (3). The reaction of (3) with tBuCCH yields the corresponding acetylide hydrido complex (7), where deuteration studies show that again the reaction does not proceed via σ-bond metathesis. Finally, treatment of (3) with HCl affords the chloro-derivative (9) [(NHC)Ti(μ-H)Ti{(μ,η5:η5)Pn†}2Cl], whereas pro- tonation with [NEt3H]BPh4 yielded a cationic hydride (10) featuring an agostic interaction between a Ti centre and an iPr Me group.

The activation of C3O2 by the U(III) complex [U(η5-Cp’)3] (Cp’ = C5H4SiMe3) is described. The reaction results in the reductive coupling of three C3O2 units to form a tetranuclear complex with a central cyclobutane-1,3-dione ring, with concomitant loss of CO. Careful control of reaction conditions has allowed the trapping of an intermediate, dimeric bridging ketene complex, which undergoes insertion of C3O2 to form the final product.

Semiconductor nanocrystals or quantum dots (QDs) are now widely used across solar cell, display, and bioimaging technologies. While advances in multishell, alloyed, and multinary core–shell QD structures have led to improved light-harvesting and photoluminescence (PL) properties of these nanomaterials, the effects that QD-capping have on the exciton dynamics that govern PL instabilities such as blinking in single-QDs is not well understood. We report experimental measurements of shell-size-dependent absorption and PL intermittency in CdSe-CdS QDs that are consistent with a modified charge-tunnelling, self-trapping (CTST) description of the exciton dynamics in these nanocrystals. By introducing an effective, core-exciton size, which accounts for delocalization of charge carriers across the QD core and shell, we show that the CTST models both the shell-depth-dependent red-shift of the QD band gap and changes in the on/off-state switching statistics that we observe in single-QD PL intensity trajectories. Further analysis of CdSe-ZnS QDs, shows how differences in shell structure and integrity affect the QD band gap and PL blinking within the CTST framework.