Student Project Abstracts 2005 - Pluto - University of Washington

determinations (XRD). The crystalline nature of these measured the average SHG counts (emitted phoproducts made for easy characterization by XRD.half the wavelength of the incoming photonSYNTHESIS OF NONLINEAR OPTICAL-ACTIVE MATERIALSTo study the feasibility of using this reaction to each area, omitting areas that did notobtain Aryl crystals, isothiocyanates racemic were 2-butanol selected because was of used their molecularfeatures. with The a aromatic variety ring of provides aryl isothiocyanates, a high number of mobile many decided to subject compared powder forms to of give our compounds rough to an relative SHGto test the In order significant to “get idea” of SHG our compounds’ activity. NLO These activity, we averagesreactionof electrons, which had which an was electron-withdrawing key for potential nonlinear group optical (EWG) applications.Unlike thiocyanates (the –S=C=N linkage), isothiocyadards:KAP and KDP.at activity test determinations.using a SHG microscope (Figure 3), with two stan-the hydrogen para bonds, position: structures phenyl molecular isothiocyanate, packing, and 4- also easier to obtain a powder than to grow crysnates feature a –R=S linkage, which builds out selected hydrogenbonds, structures molecular packing, and enhances crystal entation dependence of SHG in crystals. It was also easier to obtainUsing a powder form was a step we took to minimize the ori-fluorophenyl enhances crystal growth. isothiocyanate, In addition, the 4-chlorophenyl sulfur atom acceptable Results size and purity for other studies. Thisothiocyanate, scatters well, allowinggrowth. In addition, the4-bromophenyl absolutesulfur atom scattersisothiocyanate, X-ray structurewell, allowing absoluteX-ray structure isothiocyanate, (XRD). The crystalline4- areaa powder thanWe wasto growsucceeded (20 µm) 2crystals of acceptablein with synthesizing a step sizesize and purityand of 1forcharac µm, anitrophenyl determinationsdeterminations (XRD). and The crystalline 3-chlorophenylnature of these measurednature other studies. two The scan target the averagearea was compounds: SHG counts(20 µm) 2 with a step i-butyl-N-(4-nitro(emitted phosize of 1 µm,isothiocyanate. productsof these productsmademadefor We easyfor then easycharacterizationcharacterization performed a by second byXRD.XRD. reaction and we measuredhalf thiocarbamate thetheaveragewavelengthSHG (Fig. counts 4) of(emitted and the i-butyl-N-(4-chlorophotonsincomingof halfphotonswith To To the study costlier the the feasibility feasibility (S)-2-butanol of using of this using reaction to obtain this to obtain reaction the crys-nontals,racemic crystals, 2-butanol racemic structure. was used 2-butanol to test the reaction was used with a to variety test the areas that did significant obtained not achieve for significant SHG the SHG other activity. reactions These These averages we averages attempcentrosymmetric obtainto the wavelength each thiocarbamate of the area, incoming omitting photons) (Fig. over 5). areas each Crystalline area, that omitting did product not areaction of aryl isothiocyanates, many which had electron-withdrawinggroup (EWG) at the para position: phenyl isothiocyanate,were compared to give rough relative activity determinations.The reaction with a variety involved of mixing aryl isothiocyanates, or dissolving many the compared particular, to the give 4- rough relative aisothiocyanate of which had an in electron-withdrawing 2-butanol the aid group of vortexing. (EWG) at determinations.bromophenyl4-fluorophenyl isothiocyanate, 4-chlorophenyl RESULTSThe the4-bromophenylreaction para position: mixtureisothiocyanate,was phenyl4-nitrophenylheated isothiocyanate, inisothiocyanate,a sand bath 4- at isothiocyanate, 4-We succeeded in synthesizing and characterizing two targetabout fluorophenyland 3-chlorophenyl 110° C for isothiocyanate. 3 isothiocyanate, h, then We allowed then performed to 4-chlorophenylcool a second to room Results fluorophenylcompounds: i-butyl-N-(4-nitrophenyl) thiocarbamate (Fig. 4)temperature. isothiocyanate,reaction with the costlier Crystals 4-bromophenyl(S)-2-butanol were to obtain grown isothiocyanate,the non-centrosymmetricstructure. of the isothiocyanate, solvent. and 3-chlorophenyl two target compounds: i-butyl-N-(4-nitropby slow 4- We succeeded in synthesizing and charactand i-butyl-N-(4-chlorophenyl) thiocarbamate (Fig. 5). Crystallineproducts were obtained for the other reactions we attemptedevaporation nitrophenylctures isothiocyanate. molecular In The order reaction to packing, “get involved We an then mixing idea” and performed of dissolving our also compounds’ a the second easier isothiocyanatein 2-butanol with the aid of vortexing. The reaction mixturereaction to NLO obtain a powder thiocarbamate than to grow (Fig. crystals 4) and of i-butyl-N-(4-chlorop(in particular, the 4-bromophenyl isothiocyanate, 4-fluorophenylth. In activity, with addition, the we costlier the decided sulfur (S)-2-butanol to atom subject powder to acceptable obtain forms the size of noncentrosymmetricX-ray to an structure.SHG activity test area using was (20 a SHG µm) 2 tanol), with but a unfortunately, step obtained size of for due 1 to the µm, time other and constraints, we reactions these were we not attemptour andisothiocyanate,purity for thiocarbamateandother3-chlorophenylstudies. (Fig. Theisothiocyanate5). scan Crystallinewith (S)-2-bu-productsing was heated in a sand bath at about 110° C for 3 h, then allowed tocompounds absolutecool to room temperature. Crystals were grown by slow evaporationof the solvent.. The microscope crystalline The reaction nature characterized. The quality of the XRD structures was excellent(Figureinvolved of 3), these withmixingtwo standards: measured or dissolvingKAP the average andthe SHG counts particular, (emitted photons the of 4-characterization in most cases. As expected, the products were chiral, which isothiocyanattheKDP.isothiocyanate by XRD. in 2-butanol with the half aid the of vortexing. wavelength of the bromophenyl incoming photons) overspace groups confirmed.ility The of using reaction this mixture reaction was to heated each in a sand area, bath omitting at areas isothiocyanate, that did not achieve 4-ScanFigure 5. i-butylc 2-butanol about 110° was C for 3 h, then allowed to cool to roomstageused to test significant SHG activity. fluorophenyl These averages were chlorophenyl)of aryl temperature. isothiocyanates, Crystals many were grown compared by to slow give rough Figure relative 4. i-butyl-N-(4- activity thiocarbamate Xn-withdrawing evaporation 100x 1.3 group of N.A. the (EWG) solvent. at determinations.nitrophenyl) thiocarbamate structure. Space gphenylIn order Objective isothiocyanate,to “get an idea”4-of our 0º compounds’ or 90º NLO XRD structure. Space group: 21.activity, we decided to subject powder forms of our P 21.hiocyanate, 4-chlorophenyl Resultscompounds to an SHG activity test using a SHG3-chloromophenyl isothiocyanate, 4- We succeeded in synthesizingmicroscope (Figure 3), with two standards: isothiocyanate and characterizing with (S)-2-butanol), but unfortuDichroic800 nm KAP andyanate, and 3-chlorophenyl two target compounds:KDP.due i-butyl-N-(4-nitrophenyl)to time constraints, these were isothiocyanat noten performed mirror a second reaction thiocarbamate excitation (Fig. 4) and i-butyl-N-(4-chlorophenyl)-2-butanol to Scan obtain the nonture.obtained for the other reactions characterized. Figure we 4. i-butyl-N-(4- attempted The quality (in of the XRD structurthiocarbamate (Fig. 5). CrystallineFigure 5. i-butylchlorophenyl)Figure 4. i-butyl-N-(4-nitrophenyl) products were thiocarbamateEmission stageXRD structure. Space group: P 21.filtersthiocarbamate XRved mixing 100x or 1.3 dissolving N.A. the particular, the 4- excellent nitrophenyl) in most thiocarbamate cases. As structure. expected, Space the pgtanol with the Objective aid of vortexing. 0º bromophenyl or 90ºwere XRD chiral, structure. which Space the group: space groups 21. confirmed.was heated in a sand bath at isothiocyanate, 4- P When 21. we attempted to form i-butyl-Nthiocarbamate,we were surprised to ob3-chloro, then allowed to cool to room fluorophenylisothiocyanate with (S)-2-butanol), but unfortus were Dichroic grown by slowpreviously unseen productSingl800 nmdue to time constraints, these were notent. mirrorexcitation(according to searches ofe-idea” of our compounds’ NLOthe Cambridge StructuralPhotoo subject Emission powder forms of ourUsDatabase and SciFinder)characterized. The quality of the XRD structurG activity filters test using a SHGcontaining seven phenylexcellent in most cases. As expected, the pr, with Figure Figuretwo standards: 3. 3. SHG microscope diagram.KAP and diagram. Light of 800 nm Light wavelength of is 800 nm rings (Fig. 7).pulsed onto the sample (P = 1 or 2 mW) and the number of emitted 400Figure were 5. chiral, i-butyl-N-(4-chlorophenyl) which the space groups confirmed.wavelength is pulsed onto the sample (P = 1 or 2 mW) and It is isothiocyanate, thiocarbamateheavily conjugated andnm photons is recorded by the single-photon photomultiplier tube.When XRD structure. we Space attempted group: P 21. to form i-butyl-Nthiocarbamate,Figure 5. i-butyl-N-(4- we were surprised to obtthe number of emitted 400 nm photons is recorded by the and also chiral, and therefore predicted tosingle-photon 26 CMDITR Review photomultiplier of Undergraduate Research tube. Vol. 2 No. 1 Summer 2005previouslynonlinear opticalunseenactivity.productHowever, its crystachlorophenyl)ing a powder form was a Singl step we took Figure to minimize 4. i-butyl-N-(4- (accordingnot large enoughto searchesto performofSHG studiesthiocarbamate XRD