A growing disconnection from nature is evident in cultural products

Human connection with nature is widely believed to be in decline, even though empirical evidence on the magnitude and temporal pattern of the change is scarce. Studying works of popular culture in English throughout the 20th century and later, we document a cultural shift away from nature, beginning in the 1950s. Since then, references to nature have been decreasing steadily in fiction, song lyrics, and film storylines. No parallel decline is observed in references to the human-made environment. These findings are cause for concern, not only because they imply foregone benefits from engagement with nature, but also because cultural products are agents of socialization that can evoke curiosity, respect, and concern for the natural world

Reduced and Oxidized Forms of the Pt-Organometallic Version of Polyaniline

This work represents an effort to synthesize all four forms of polyaniline (PANI) in its organometallic versions. Polymers containing substituted 1,4-benzoquinone diimine or 1,4-diaminobenzene units in the backbone exhibiting the general structure (C CC6H4-N=C6X4=N-C6H4C C-PtL2) and (C CC6H4NH-C6X4NHC6H4C C-PtL2) along with the corresponding model compounds (C CC6H4-N=C6X4=N-C6H4C C)-(PtL2Cl)(2) and (C CC6H4NH-C6X4-NHC6H4C C)-(PtL2Cl)(2) (L = PBu3; X = H, F, Cl) were synthesized. The polymers and corresponding model compounds were characterized (including H-1 and P-31 NMR, IR, mass spectra, elemental analysis, and X-ray structure determinations) and investigated for their redox properties in the absence and in the presence of acid. Their optical properties, including ns transient spectroscopy were also investigated. These properties were interpreted through density functional theory (DFT) and time-dependent DFT (TDDFT) computations. These materials are found to be oligomers (GPC) with thermal stability (TGA) reaching 350 degrees C. The greatest stabilities were found in the cases with X = F. Using a data bank of 8 X-ray structures of diimine derivatives, a relationship between the C=N bond distance and the dihedral angle between the benzoquinone ring and the flanking phenyl planes is noted. As the size of the substituent X on the benzoquinone center increases, the degree of conjugation decreases as demonstrated by the C=N bond length. The largest dihedral angles are noted for X = Cl. These polymers exhibit drastic chemical differences when X is varied (X = H, F, Cl). The completely reduced polymer (C CC6H4NH-C6H4-NHC6H4C C-PtL2) (i.e., X = H) was not chemically accessible whereas in the cases of X = F, Cl, these materials were obtained and represent the first examples of fully reduced organometallic versions of PANI (i.e., leucoemaraldine). For the (C CC6H4-N=C6X4=N-C6H4C C-PtL2) polymers, the completely oxidized form for X = H was isolated (pemigraniline), but for X = F and Cl, only the largely reduced mixed-valence form (i.e., emaraldine) was obtained via chemical routes. In acidic solutions, the chemically accessible polymer for X = H, (C CC6H4-N=C6H4=N-C6H4C C-PtL2), exhibits two chemically reversible waves indicating that the reduced form (C CC6H4NH-C6H4-NHC6H4C C-PtL2) can be generated. The absorption spectra of the highly colored diimine-containing species exhibit a broad charge transfer band (assigned based on DFT calculations (B3LYP); C6H4C C-PtL2-C CC6H4 -> N=C6X4=N) in the 450-800 nm window red shifting according X = H -> Cl -> F, consistent with their relative inductive effect. The largest absorptivity is measured for X = H because this polymer is fully oxidized whereas for the cases where X = F and Cl, these polymers exists in the mixed valence form. The ns transient absorption spectra of two polymers (X = F; reduced and mixed-valence polymers) were measured. The triplet excited state in the mixed-valence polymer is dominated by the reduced diamine residue and the T-1-T-n absorption of the diimine is entirely quenched