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Toward Tetraradicaloid: The Effect of Fusion Mode on Radical Character and Chemical Reactivity
Hu, Pan,Lee, Sangsu,Herng, Tun Seng,Aratani, Naoki,Gonç,alves, Thé,o P.,Qi, Qingbiao,Shi, Xueliang,Yamada, Hiroko,Huang, Kuo-Wei,Ding, Jun,Kim, Dongho,Wu, Jishan American Chemical Society 2016 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.138 No.3
<P>Open-shell singlet diradicaloids display unique electronic, nonlinear optical, and magnetic activity and could become novel molecular materials for organic electronics, photonics, and spintronics. However, design and synthesis of diradicaloids with a significant polyradical character is a challenging task for chemists. In this Article, we report our efforts toward a tetraradicaloid system. A series of potential tetraradicaloids by fusion of two p-quinodimethane (p-QDM) units with naphthalene or benzene rings in different modes were synthesized. Their model compounds containing one p-QDM moiety were also prepared and compared. Their ground-state structures, physical properties, and chemical reactivity were systematically investigated by various experimental methods such as steady-state and transient absorption, two-photon absorption, X-ray crystallographic analysis, electron spin resonance, superconducting quantum interference device, and electrochemistry, assisted by density functional theory calculations. It was found that their diradical and tetraradical characters show a clear dependence on the fusion mode. Upon the introduction of more five-membered rings, the diradical characters greatly decrease. This difference can be explained by the pro-aromaticity/antiaromaticity of the molecules as well as the intramolecular charge transfer. Our comprehensive studies provide a guideline for the design and synthesis of stable open-shell singlet polycyclic hydrocarbons with significant polyradical characters.</P>
Hu, Pan,Lee, Sangsu,Park, Kyu Hyung,Das, Soumyajit,Herng, Tun Seng,Gonç,alves, Thé,o P.,Huang, Kuo-Wei,Ding, Jun,Kim, Dongho,Wu, Jishan American Chemical Society 2016 Journal of organic chemistry Vol.81 No.7
<P>The fundamental relationship between structure and diradical character is important for the development of open-shell diradicaloid-based materials. In this work, we synthesized two structural isomers bearing a 2,6-naphthoquinodimethane or a 1,5-naphthoquinodimethane bridge and demonstrated that their diradical characters and chemical reactivity are quite different. The mesityl-or pentafluorophenyl-substituted octazethrene derivatives <B>OZ-M/OZ-F</B> and their isomer <B>OZI-M</B> (with mesityl substituents) were synthesized via an intramolecular Friedel–Crafts alkylation followed by oxidative dehydrogenation strategy from the key building blocks <B>4</B> and <B>11</B>. Our detailed experimental and theoretical studies showed that both isomers have an open-shell singlet ground state with a remarkable diradical character (<I>y</I><SUB>0</SUB> = 0.35 and 0.34 for <B>OZ-M</B> and <B>OZ-F</B>, and <I>y</I><SUB>0</SUB> = 0.58 for <B>OZI-M</B>). Compounds <B>OZ-M</B> and <B>OZ-F</B> have good stability in an ambient environment, while <B>OZI-M</B> has high reactivity and can be easily oxidized to a dioxo product <B>15</B>, which can be correlated to their different diradical characters. Additionally, we investigated the physical properties of <B>OZ-M</B>, <B>OZ-F</B>, and <B>15</B>.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/joceah/2016/joceah.2016.81.issue-7/acs.joc.6b00172/production/images/medium/jo-2016-00172x_0011.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jo6b00172'>ACS Electronic Supporting Info</A></P>
A 4x Time-Domain Interpolation 6-bit 3.4 GS/s 12.6 ㎽ Flash ADC in 65 ㎚ CMOS
Jianwei Liu,Chi-Hang Chan,Sai-Weng Sin,Seng-Pan U,Rui Paulo Martins 대한전자공학회 2016 Journal of semiconductor technology and science Vol.16 No.4
A 6-bit 3.4 GS/s flash ADC in a 65 ㎚ CMOS process is reported along with the proposed 4x time-domain interpolation technique which allows the reduction of the number of comparators from the conventional 2<SUP>N</SUP>-1 to 2<SUP>N-2</SUP> in a N-bit flash ADC. The proposed scheme effectively achieves a 4x interpolation factor with simple SR-latches without extra clocking and calibration hardware overhead in the interpolated stage where only offset between the 2<SUP>N-2</SUP> comparators needs to be calibrated. The offset in SR-latches is within ±0.5 LSB in the reported ADC under a wide range of process, voltage supply, and temperature (PVT). The design considerations of the proposed technique are detailed in this paper. The prototype achieves 3.4 GS/s with 5.4-bit ENOB at Nyquist and consumes 12.6 ㎽ power at 1 V supply, yielding a Walden FoM of 89 fJ/conversion-step.
A 4x Time-Domain Interpolation 6-bit 3.4 GS/s 12.6 mW Flash ADC in 65 nm CMOS
Liu, Jianwei,Chan, Chi-Hang,Sin, Sai-Weng,U, Seng-Pan,Martins, Rui Paulo The Institute of Electronics and Information Engin 2016 Journal of semiconductor technology and science Vol.16 No.4
A 6-bit 3.4 GS/s flash ADC in a 65 nm CMOS process is reported along with the proposed 4x time-domain interpolation technique which allows the reduction of the number of comparators from the conventional $2^N-1$ to $2^{N-2}$ in a N-bit flash ADC. The proposed scheme effectively achieves a 4x interpolation factor with simple SR-latches without extra clocking and calibration hardware overhead in the interpolated stage where only offset between the $2^{N-2}$ comparators needs to be calibrated. The offset in SR-latches is within ${\pm}0.5$ LSB in the reported ADC under a wide range of process, voltage supply, and temperature (PVT). The design considerations of the proposed technique are detailed in this paper. The prototype achieves 3.4 GS/s with 5.4-bit ENOB at Nyquist and consumes 12.6 mW power at 1 V supply, yielding a Walden FoM of 89 fJ/conversion-step.