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Two giant calix[n]phyrin derivatives namely calix- [8]- (4) and calix[16]phyrin (5), involving two and four BF2 units, respectively, were prepared through the condensation of the bis-naphthobipyrrolylmethene-BF2 complex (3) with pentafluorobenzaldehyde. Calix[n]phyrins 4 and 5 display extremely high extinction coefficients (3.67 and 4.82  105m1cm1, respectively) in the near-IR region, which was taken as initial evidence for strong excitonic coupling within these cyclic multi-chromophoric systems. Detailed insights into the effect of excitonic coupling dynamics on the electronic structure and photophysical properties of the macrocycles came from fluorescence, time-correlated single-photon counting (TCSPC) and transient absorption (TA) measurements. Support for these experimental findings came from theoretical studies. Theory and experiment confirmed that the coupling between the excitons depends on the specifics of the calix- [n]phyrin structure, not just its size. 

Understanding of interactions among molecules is essential to elucidate the binding of pharmaceuticals on receptors, the mechanism of protein folding and self-assembling of organic molecules. While interactions between two aromatic molecules have been examined extensively, little is known about the interactions between two antiaromatic molecules. Theoretical investigations have predicted that antiaromatic molecules should be stabilized when they stack with each other by attractive intermolecular interactions. Here, we report the synthesis of a cyclophane, in which two antiaromatic porphyrin moieties adopt a stacked face-to-face geometry with a distance shorter than the sum of the van der Waals radii of the atoms involved. The aromaticity in this cyclophane has been examined experimentally and theoretically. This cyclophane exhibits three-dimensional spatial current channels between the two subunits, which corroborates the existence of attractive interactions between two antiaromatic π-systems.

 

Although metal halide perovskite (MHP) light‐emitting diodes (LEDs) have demonstrated great potential in terms of electroluminescence efficiency, the operational stability of MHP LEDs currently remains the biggest bottleneck toward their practical usage. Well‐confined excitons/charge carriers in a dielectric/quantum well based on conventional spatial or potential confinement approaches substantially enhance radiative recombination in MHPs, but an increased surface‐to‐volume ratio and multiphase interfaces likely result in a high degree of surface or interface defect states, which brings about a critical environmentally/operationally vulnerable point on LED stability. Here, an effective solution is suggested to mitigate such drawbacks using strategically designed surface‐2D/bulk‐3D heterophased MHP nanograins for long‐term‐stable LEDs. The 2D surface‐functionalized MHP renders significantly reduced trap density, environmental stability, and an ion‐migration‐immune surface in addition to a fast radiative recombination owing to its spatially and potentially confined charge carriers, simultaneously. As a result, heterophased MHP LEDs show substantial improvement in operational lifetime (T₅₀: >200 h) compared to conventional pure 3D or quasi‐2D counterparts (T₅₀: < 0.2 h) as well as electroluminescence efficiency (surface‐2D/bulk‐3D: ≈7.70 ph per el% and pure 3D: ≈0.46 ph per el%).

 

A new expanded porphycene with 26 π‐electrons has been prepared by the McMurry coupling of 1,4‐bis(3,4‐diethyl‐2‐pyrryl)benzene dialdehyde. Expansion of the porphycene framework provides a ligand capable of stabilizing a bis(rhodium) and a monoruthenium complex. These new porphycene derivatives absorb strongly in the NIR spectral region, with appreciable absorptivity up to 1300 nm. On the basis of their ground‐ and excited‐state spectroscopic features and structural parameters, both the free‐base system and the bis(rhodium) complex are considered to be Hückel‐type aromatic systems. This conclusion is supported by DFT calculations.

 

A new expanded porphycene with 26 π‐electrons has been prepared by the McMurry coupling of 1,4‐bis(3,4‐diethyl‐2‐pyrryl)benzene dialdehyde. Expansion of the porphycene framework provides a ligand capable of stabilizing a bis(rhodium) and a monoruthenium complex. These new porphycene derivatives absorb strongly in the NIR spectral region, with appreciable absorptivity up to 1300 nm. On the basis of their ground‐ and excited‐state spectroscopic features and structural parameters, both the free‐base system and the bis(rhodium) complex are considered to be Hückel‐type aromatic systems. This conclusion is supported by DFT calculations.