A record value of the current rectification ratio (RR ≥ 105) across molecularly doped thin films of a Cu(ii)-coordination polymer is achieved.

No abstract

Concave cuboid (CCB) nanostructure is a member of the high-index facet (HIF) nanocrystals (NCs) family, geometrically derived from regular cuboid-excavation of each face. CCB NCs hold some additional characteristics such as surface cavity and sharp edges and corners as compared to its convex counterpart that makes it relatively more active in applications like electrochemical catalysis, surface enhanced Raman spectroscopy (SERS), and plasmonics. To date, there are only few reports available on the synthesis of CCB Au NCs where Br– containing surfactants have been used as a shape directing and stabilizing agent. However, none of them led to decent yield and size tunability. Herein, we report a robust seed mediated growth strategy where cetyltrimethylammonium chloride (CTAC) and tannic acid (TA) have been used as shape-directing/stabilizing and mild reducing agents, respectively. Our method not only allows the high yield fabrication of CCB Au NCs with uniform shape and size but also precise control over dimensions and degree of surface concavity. Moreover, the investigation of growth mechanism revealed that the evolution of CCB Au NCs from cylindrical nanorods (NRs) take place via arrow-headed nanorods and truncated CCB nanostructures. Furthermore, it has been observed that the presence of excess of Cl– is indeed playing a decisive role despite the headgroup of counter cationic part of surfactant. We anticipate that our findings may pave the path to design new synthetic strategies and understand the evolution of new nanostructures.

Wet-chemical fabrication of a crystalline Ag-TCNQ (TCNQ = 7,7,8,8-tetracyanoquinodimethane) thin film on non-Ag substrate is challenging whereby the chemistry was powered by photon energy and/or electrical energy. We report for the first time, direct chemical growth of a Ag-TCNQ thin film on a functionalized Au substrate by employing the layer-by-layer (LbL) approach at ambient reaction conditions. Various Ag­(I) salt precursors previously realized to be unsuitable for the fabrication of Ag-TCNQ thin films on non-Ag substrates ultimately gave rise to dense and uniform thin films of Ag-TCNQ. The crucial knob regulating the direct formation of the thin films of Ag-TCNQ was identified to be the pH of the respective Ag­(I) solutions.

Among various factors playing pivotal roles in the typical seed-mediated growth of Au nanocrystals (NCs), the role of Ag (AgNO3) has remained debatable over time and seminal research efforts have helped us in reaching a consensus, albeit from the standpoint of [Ag+] concentration. This study aims to provide an understanding of the role of Ag+ from the perspective of time. Here, we show that different Au NCs with tunable aspect ratios (ARs) can be generated in one system in high yield simply by varying the time of addition of Ag+ in the growth solution. The generality of the method has been demonstrated in tuning the ARs of anisotropic Au NCs like concave cuboid (CCB, AR = 2) and elongated tetrahexahedra (AR = 2.5), where the delayed addition of Ag+ leads to the formation of their isotropic counterpart concave cube (CC, AR = 1) and tetrahexahedra (AR = 1), respectively. This work, apart from establishing timed addition of Ag+ as a crucial parameter in controlling the AR, may also help in the realization of a universal growth mechanism of Au NCs. The Au NCs with varying ARs (CCB, AR = 2 and CC, AR = 1) have been further explored as potential substrates for surface-enhanced Raman scattering (SERS) due to the presence of their high-index facets and sharp tips.