Optical activity, a foundational part of chemistry, is not restricted to chiral molecules although generations have been instructed otherwise. A more inclusive view of optical activity is valuable because it...
Optical rotations and rotatory strengths are calculated for achiral, conjugated hydrocarbons with the aim of determining to what extent the sum-over-π → π* rotatory strengths are sufficient to account for nonresonant optical activity. The separability of σ and π electrons might provide a short cut to the interpretation of chiroptical structure-property relations in some cases. It is shown that by restricting the analyses to planar, C(2v)-symmetric π-systems and their one electron HOMO-LUMO excitations, an intuitive understanding of the vexing property of optical activity is forthcoming for the following reasons: Hückel wave functions are simply calculated, and in some cases, they can even be approximated by inspection of structure. Wave functions of planar molecules can be multiplied with one another graphically or, in the mind's eye, to yield transition electric and magnetic moments. The gyration tensors have just one independent component. Transition dipole moments are orthogonal to one another. And, the most optically active directions are found at their bisectors. Throughout, emphasis is on the evaluation of long wavelength optical rotation, consistent with quantum chemical computation, using simple models that are part of the fabric of organic chemistry pedagogy.
Pediatricians regularly care for children who have experienced child maltreatment. Child maltreatment is a risk factor for a broad range of mental health problems. Issues specific to child maltreatment make addressing emotional and behavioral challenges among maltreated children difficult. This clinical report focuses on 2 key issues necessary for the care of maltreated children and adolescents in pediatric settings: trauma-informed assessments and the role of pharmacotherapy in maltreated children and adolescents. Specific to assessment, current or past involvement of the child in the child welfare system can hinder obtaining necessary information or access to appropriate treatments. Furthermore, trauma-informed assessments can help identify the need for specific interventions. Finally, it is important to take both child welfare system and trauma-informed assessment approaches into account when considering the use of psychotropic agents because there are critical diagnostic and systemic issues that affect the prescribing and discontinuing of psychiatric medications among children with a history of child maltreatment.
Comparisons are made of the calculated optical rotation tensors of C(2v)-symmetric, polyaromatic hydrocarbons and their [5]helicene, [6]helicene, and [7]helicene isomers. Seven ∩-shaped, planar compounds had, in each case, larger computed tensor elements than the chiral helicenes. Merely obviating the condition of solution averaging wholly changes expectations of the magnitudes and etiologies of optical activity. Symmetries of achiral compounds facilitate semiquantitative correlations between structure and optical rotation.
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