@article{reuther_bhatt_tian_batchelor_campos_novak_2014, title={Controlled Living Polymerization of Carbodiimides Using Versatile, Air-Stable Nickel(II) Initiators: Facile Incorporation of Helical, Rod-like Materials}, volume={47}, ISSN={["1520-5835"]}, DOI={10.1021/ma5009429}, abstractNote={The new polymerization of carbodiimides using two, simple [bis(triphenylphosphino)aryl]nickel(II) bromide complexes has been discovered to occur in a controlled, living fashion. These initiators are substantially more air and moisture stable compared to their titanium(IV) counterparts making them significantly easier to synthesize, purify, and utilize. The polymerization is initiated via aryl ligand transfer to the electrophilic center carbon of the carbodiimide. Sequential insertions of the carbodiimide π-bond into the nickel–nitrogen amidinate coordination bond propagates the polymer chain in a living chain growth manner as evident by the linear relationship in the plots of percent conversion vs Mn, ln([M]o/[M]) vs time, and monomer: initiator ratio vs Mn. The transferred aryl ligand was confirmed to be appended to the terminus of the polymer chain by MALDI–TOF and 19F NMR. This added control element offers new opportunities to end functionalize rigid-rod, helical polycarbodiimides. This new technique a...}, number={14}, journal={MACROMOLECULES}, author={Reuther, James F. and Bhatt, Mahesh P. and Tian, Gonglu and Batchelor, Benjamin L. and Campos, Raymond and Novak, Bruce M.}, year={2014}, month={Jul}, pages={4587–4595} }
 @article{kennemur_clark_tian_novak_2010, title={A New, More Versatile, Optical Switching Helical Polycarbodiimide Capable of Thermally Tuning Polarizations +/- 359 degrees}, volume={43}, ISSN={["1520-5835"]}, DOI={10.1021/ma902657d}, abstractNote={An in depth study of newly synthesized polycarbodiimides containing asymmetric aryl pendant groups has been performed. The focus of this study was to create new polymers capable of the low-energy, reversible, solvo-, and thermocontrollable conformational switching phenomenon previously discovered. Of the polymers synthesized, one polymer, N-(1-naphthyl)-N′-(n-octadecyl) polycarbodiimide, Poly-5, has been found to undergo reversible optical switching in various solvents, each of which alter the temperature at which the switching is observed. The switching is not due to helical inversions, but instead due to synchronous rearrangement of polyarene pendant groups around the helical backbone. This is further shown by anisotropic changes of the aromatic chemical shifts using variable temperature 1H NMR through the observed thermal switching range in THF-d8. The net change in specific optical rotation reaches a remarkable 1700° and changes in the direction of rotation. The polymer system is tunable and capable o...}, number={4}, journal={MACROMOLECULES}, author={Kennemur, Justin G. and Clark, J. B. and Tian, Gonglu and Novak, Bruce M.}, year={2010}, month={Feb}, pages={1867–1873} }
 @article{tian_lu_novak_2004, title={Helix-sense selective polymerization of carbodiimides: Building permanently optically active polymers from achiral monomers}, volume={126}, ISSN={["1520-5126"]}, DOI={10.1021/ja049548m}, abstractNote={The helix-sense selective polymerization of achiral monomers by homochiral catalysts was investigated. Polymerization of chiral carbodiimides (N-(R)-2,6-(dimethylheptyl)-N'-phenylcarbodiimide) by achiral catalysts yields polymers that undergo mutorotation at elevated temperatures, thus illustrating that these chains are formed under kinetic rather than thermodynamic control. Building on this observation, the polymerization of achiral carbodiimides by (S-BINOL)Ti(OiPr)2, I, was studied. Monomers (N-hexyl-N'-(X)carbodiimide, where X = isopropyl (3), hexyl (4) or phenyl (5)), N-methyl-N'-(2-methyl-6-isopropylphenyl)carbodiimide, 6, and N-dodecyl-N'-(1-naphthyl)carbodiimide, 7, were all polymerized with I in good yields (86-95%), and all showed varying degrees of asymmetric induction. Poly-3, -4, and -5 racemized upon heating at elevated temperatures, but poly-6 and poly-7, bearing nonsymmetric phenyl groups, yielded optically active polymers that could not be racemized even at elevated temperatures. Thin films of poly-7 were found to be highly opalescent.}, number={13}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, author={Tian, GL and Lu, YJ and Novak, BM}, year={2004}, month={Apr}, pages={4082–4083} }
 @article{tian_boyle_novak_2002, title={Synthesis and crystal structure of a dinuclear palladium complex containing C,O-bridging ester-enolato moieties}, volume={21}, ISSN={["1520-6041"]}, DOI={10.1021/om010968j}, abstractNote={Palladium ester enolates have been prepared and characterized using IR, NMR, and single-crystal X-ray diffraction techniques. The X-ray diffraction established a dimeric crystal structure for complex {[N∧N]PdCH2C(O)OCH3}2 (N∧N = 1-[1-(5-methylpyrrole-2-yl)ethylidne]amino-2,6-diisopropylbenzene), 2, which contains C,O-bridging enolato groups. Upon reaction with donor molecules (acetonitrile, phosphines), the dimeric 2 cleaves to form monometallic C-bound enolate complexes, 3‘ and 4.}, number={7}, journal={ORGANOMETALLICS}, author={Tian, GL and Boyle, PD and Novak, BM}, year={2002}, month={Apr}, pages={1462–1465} }
 @article{tian_boone_novak_2001, title={Neutral palladium complexes as catalysts for olefin-methyl acrylate copolymerization: A cautionary tale}, volume={34}, ISSN={["0024-9297"]}, DOI={10.1021/ma010857w}, abstractNote={Neutral palladium complexes bearing pyrrole−imine ligands (I−III) have been synthesized, and their use as catalysts for olefin and vinyl monomer (co)polymerizations was investigated. Methyl acrylate (MA) has been homopolymerized in excellent yields (>95%) using these complexes. Copolymerizations of MA with norbornene or 1-hexene in the presence of these catalysts produce acrylate-enriched copolymers. Hypothesizing that metal enolates are potential intermediates in some of these polymerizations, palladium enolate complexes (IV−VII) containing ligand 1 were tested for their catalytic activity. Surprisingly, these complexes proved inactive toward acrylate and/or olefin polymerizations. Further mechanistic studies have shown that the homo- and copolymers obtained using these complexes arise from a radical mechanism rather than the anticipated metal-mediated process.}, number={22}, journal={MACROMOLECULES}, author={Tian, GL and Boone, HW and Novak, BM}, year={2001}, month={Oct}, pages={7656–7663} }