X-ray crystal structure of 1,4-diphenylbutadiyne

Surette, Jacqueline K. D.; MacDonald, Mary-Anne; Zaworotko, Michael J.; Singer, Robert D.

doi:10.1007/bf01668237

Cited by 18 publications

(12 citation statements)

References 6 publications

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“…Based on the theoretical and empirical research on three-strikes legislation and with the recognition that policy making is inherently a political process, we offer the following suggestions for policymakers and criminal justice researchers. First, legislators should be aware of "claimsmakers" and media distortion of social problems (Cohen, 1972;Fishman, 1976;Kappler et al, 1996;McCorkle and Miethe, 2002;Surette, 1998) and resist passing "quick fix" solutions in a climate of public fear. Second, policy makers should take more care to weigh, not just the potential benefits of a proposed crime control solution, but the potential costs as well, and researchers should become more active in providing assistance in this process.…”

Section: Discussionmentioning

confidence: 99%

Unintended Consequences of Politically Popular Sentencing Policy: The Homicide Promoting Effects of “Three Strikes” in U.S. Cities (1980–1999)*

Kovandzic

Sloan

Vieraitis

2002

Criminology & Public Policy

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Research Summary:Using panel data from 188 large cities during 1980-1999, we examined the possible homicide promoting effects of "three-strikes" laws. Results indicated that cities in states with three-strikes laws experienced short-term increases in homicide rates of 13% to 14% and longterm increases of 16% to 24% compared with cities in states without the laws. Policy Implications:Our results emphasize the fact that rarely are the possible unintended negative consequences of policy directives considered and point to the need for policy makers to consider both intended and unintended consequences of policy directives before the directives are codified.Intuitively, most people, and lately most legislators, presume that lengthy imprisonment, determinate sentencing, mandatory minimum sentencing, and severe habitual offender laws offer safety along with retribution. But as criminologists and other social scientists have often shown, intuition alone isn't a sound basis for judging what will or won't work, at what cost, and with what side effects [emphasis added] (Skolnick, 1995:3). Facing intense public pressure to address the problem of high violent crime rates in the late 1980s and early 1990s, policy makers responded by strengthening existing laws targeting repeat offenders. Between 1993 and 1996, a total of 25 states and the federal government enacted what are * We thank Thomas Marvel1 and Francis T. Cullen for their encouragement and assistance with this project, but note that we alone bear responsibility for any errors remaining in the paper. Send correspondence to Tomislav V. Kovandzic,

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Section: Discussionmentioning

confidence: 99%

Unintended Consequences of Politically Popular Sentencing Policy: The Homicide Promoting Effects of “Three Strikes” in U.S. Cities (1980–1999)*

Kovandzic

Sloan

Vieraitis

2002

Criminology & Public Policy

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“…The resonance stabilisation in DPDA is demonstrably lowerthe calculated BLA is the same in perpendicular and planar conformers. [69][70][71][72][73][74][75] θ = 0° 0.178 ± 0.011…”

Section: Evidence For Enhanced Conjugation In the Planar Conformer From C≡c Bond Length And Vibrational Frequenciesmentioning

confidence: 99%

Experimental and computational evaluation of the barrier to torsional rotation in a butadiyne-linked porphyrin dimer

Peeks

Neuhaus

Anderson

2016

Phys. Chem. Chem. Phys.

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The barrier to torsional rotation in a butadiyne-linked porphyrin dimer has been determined in solution using variable temperature UV-vis-NIR spectroscopy: ΔH = 5.27 ± 0.03 kJ mol(-1), ΔS = 10.69 ± 0.14 J K(-1) mol(-1). The value of ΔH agrees well with theoretical predictions. Quantum chemical calculations (DFT) were used to predict the torsion angle dependence of the absorption spectrum, and to calculate the vibronic fine structure of the S0 → S1 absorption for the planar dimer, showing that the absorption band of the planar conformer has a vibronic component overlapping with the 〈0|0〉 absorption of the perpendicular conformer. The torsion barrier in the porphyrin dimer is higher than that of 1,4-diphenylbutadiyne (calculated ΔH = 1.1 kJ mol(-1)). Crystallographic bond lengths and IR vibrational frequencies confirm that there is a greater contribution of the cumulenic resonance form in butadiyne-linked porphyrin dimers than in 1,4-diphenylbutadiyne. The DFT frontier orbitals of the twisted conformer of the porphyrin dimer are helical, when calculated in the absence of symmetry. The helical character of these orbitals disappears when D2d symmetry is enforced in the 90° twisted conformer. Helical representations of the frontier orbitals can be generated by linear combinations of the more localised orbitals from a symmetry-constrained calculation but they do not indicate π-conjugation. This work provides insights into the relationship between electronic structure and conformation in alkyne-linked conjugated oligomers.

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“…10.4u around the C(2)-C(3) bond and 13.2u around the C(16)-C( 19) bond. It is noteworthy that the unsubstituted 1,4-diphenylbutadiyne is planar as a pure solid, 20 in co-crystals with perfluoro-1,4-diphenylbutadiyne, 21 and in an acetylide Cu 4 cluster, 22 whilst in 1,4-bis(4-nitrophenyl)butadiyne the two benzene rings are perpendicular. 23 However, the conformation has no appreciable effect on the bond distances in the butadiyne moiety, which coincide, within experimental error, in all diphenylbutadiyne derivatives, including 6.…”

Section: Crystal Structuresmentioning

confidence: 99%

Synthesis, optical properties, crystal structures and phase behaviour of symmetric, conjugated ethynylarene-based rigid rods with terminal carboxylate groups

et al. 2005

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X-ray crystal structure of 1,4-diphenylbutadiyne

Cited by 18 publications

References 6 publications

Unintended Consequences of Politically Popular Sentencing Policy: The Homicide Promoting Effects of “Three Strikes” in U.S. Cities (1980–1999)*

Unintended Consequences of Politically Popular Sentencing Policy: The Homicide Promoting Effects of “Three Strikes” in U.S. Cities (1980–1999)*

Experimental and computational evaluation of the barrier to torsional rotation in a butadiyne-linked porphyrin dimer

Synthesis, optical properties, crystal structures and phase behaviour of symmetric, conjugated ethynylarene-based rigid rods with terminal carboxylate groups

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