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  1. 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.
  2. The third industrial revolution has brought mankind into the information age. The development of information storage materials has played a key role in this transformation. Such materials have seen use in many application areas, including computing, logistics, and medicine. Information storage materials run the gamut from magnetic information storage media to molecular-based information storage materials. Among these, fluorescent-based information storage materials are of particular interest due to their unique properties, including an ability to store information with high levels of security, maintain mechanical stability, and respond to appropriately chosen external stimuli. In this review, we focus on recent advances involving the preparation and study of fluorescent materials-based information storage codes. For organisational purposes, these codes are treated according to the dimensionality of the code system in question, namely 1D-, 2D-, and 3D-type codes. The present review is designed to provide a succinct summary of what has been accomplished in the area, while outlining existing challenges and noting directions for future development.
  3. β,β′-Phenylene bridged hexaphyrin[] (naphthorosarin), an expanded porphyrin possessing C 3v -symmetry, has been shown to possess unique electronic features. We now report a bimetallic Rh( i )-complex of naphthorosarin retaining 24 π-antiaromatic characteristics. The two Rh( i ) cations reside on opposite sides of the macrocyclic π-system and are separated at a distance consistent with a possible Rh( i )–Rh( i ) metallic bond interaction.
  4. The synthesis and characterization of the alkylidenyl-dibenzihexaphyrins bearing four indanedionyl groups at the meso -positions linked via four meso -exocyclic double bonds is reported. Treatment with trifluoroacetic acid at 50 °C leads to C(α)-protonation of the two indanedionyl groups resulting increased macrocyclic conjugation with dramatic red shifted absorption spectra.
  5. The photophysical properties of naturally occurring chlorophylls depend on the regioisomeric nature of the β-pyrrolic substituents. Such systems are the “gold standard” by which such effects are judged. However, simple extrapolations from what has been learned with chlorophylls may not be appropriate for other partially reduced porphyrinoids. Here we report the synthesis of a series of cis / trans -porphodilactones ( cis / trans -1) and related derivatives ( cis / trans 2–5) designed to probe the effect of regioisomeric substitution in porphyrinoids that incorporate degrees of unsaturation through the β-pyrrolic periphery that exceed those of chlorophyll. These test systems were obtained through β-pyrrolic modifications of the tetrapyrrolic core, which included reduction of β-diazalone to the corresponding dilactol moieties and 1,3-dipolar cycloadditions. In the case of cis - vs. trans -3 bearing two pyrrolidine-fused β-rings we found an unprecedented Δ Q L up to ca. 71 nm (2086 cm −1 ), where Δ Q L ( Q L means the lowest energy transfer band, also the S 0 → S 1 transition band, which is often assigned as Q y (0,0) band) refers to the transition energy difference between the corresponding cis / trans -isomers. The Δ Q L valuesmore »for these and other systems reported here were found to depend on the differences in the HOMO–LUMO energy gap and to be tied to the degeneracy and energy level splitting of the FMOs, as inferred from a combination of MCD spectral studies and DFT calculations. The aromaticity, estimated from the chemical shifts of the N–H protons and supported by theoretical calculations ( e.g. , AICD plots and NICS(1) values), was found to correlate with the extent of porphyrin periphery saturation resulting from the specific β-modifications. The aromaticity proved inversely proportional to the degree to which the regioisomerism affected the photophysical properties as noted from plots of Δ Q L s in cm −1 vs. the average NICS(1) values for 1–5. Such a finding is not something that can be easily interpolated from prior work and thus reveals how aromaticity may be used to fine-tune photophysical effects in reduced porphyrinoids.« less