Pol ish J. Chem., 82, 647 (2008)

Transcription

1 Pol ish J. Chem., 82, 647 (2008) Pro fes sor Zbigniew Ryszard Grabowski holds a very spe - cial place in sci ence. In the pho to chem i cal com mu nity, his name is in sep a ra ble from the term he coined three de cades ago: TICT. Af ter years of thor ough, of ten emo tional dis cus - sions, the con cept of Twisted Intra molecular Charge Trans - fer ex cited states seems to be well es tab lished. Re search ers of ten (per haps too of ten!) evoke conformational changes in photoexcited flex i ble elec tron do nor-ac cep tor sys tems to in - ter pret the com plex be hav iour (dual flu o res cence in par tic u lar) of their mol e cules. Start ing his car rier al ready as a stu dent, at the Chem is try De part ment of the War - saw Uni ver sity, Z.R. Grabowski did re search on elec trode ki net ics and on stereo - chemistry of elec trode pro cesses. He dis cov ered the ef fects of elec tric field strength on elec trode re ac tions mech a nisms. Founder of the Photochemistry and Spec tros copy Lab o ra tory in the In sti tute of Phys i cal Chem is try of the Pol ish Acad emy of Sci ences, he con trib uted to the de vel - op ment (in co op er a tion with Jan Jasny and Józef Koszewski) of unique spec tral in - stru ments for ab sorp tion and lu mi nes cence mea sure ments. In the field of ex cited state acid-base equi lib ria, his name is as so ci ated with the so-called gen er al ized Förster cy cle, the idea he pro moted to gether with wife Anna. Yet an other area of his pas sions and sci en tific ac tiv i ties in cludes the chem i cal evo lu tion and or i gins of life, sub jects re lated to astrochemistry. We were given a chance to do our PhDs, to work, and to ma ture in the lab o ra tory of Pro fes sor Grabowski. Not only did he teach us that sci ence should be done with no com pro mise, but also that sci en tists du ties ex tend be yond pure re search. Ac tively in - volved in mat ters cru cial for the so ci ety, he is hav ing the cour age to speak out boldly against any in jus tice set ting ex am ples that are not al ways easy to fol low. This spe cial is sue of the Pol ish Jour nal of Chem is try con tains con tri bu tions from stu dents, as so ci ates, and friends of Pro fes sor Grabowski. We all want to con grat u late him on his birth day. Many happy re turns, Zbyszku! Jerzy Herbich Rob ert Ko³os Jacek Waluk

2 Pol ish J. Chem., 82, (2008) Quan tum Chem i cal Study of Hydroxylation of Al kanes by Hypofluorous Acid by M. Onèák 1, M. Srnec 2** and R. Zahradník 1** 1 J. Heyrovský In sti tute of Phys i cal Chem is try, v.v.i., Acad emy of Sci ences of the Czech Re pub lic, Dolejškova St. 3, Prague 8, Czech Re pub lic 2 In sti tute of Or ganic Chem is try and Bio chem is try, v.v.i., Acad emy of Sci ences of the Czech Re pub lic, Flemingovo Sq., Prague 6, Czech Re pub lic ** m.srnec@seznam.cz or rudolf.zahradnik@jh-inst.cas.cz (Re ceived No vem ber 1st, 2007; ac cepted No vem ber 9th, 2007) The ex per i men tally ob served hydroxylation of al kanes by hypofluorous acid (one of Rozen s ox i da tion re ac tions) was in ves ti gated us ing the meth ods of quan tum chem is try. It was shown that the high ef fi ciency of the re ac tion may be ex plained by self-ca tal y sis. The ox i diz ing HOF mol e cule trans fers the ox y gen atom to a sub strate, which is ac com pa - nied by the HF for ma tion, while the sec ond hypofluorous acid mol e cule sta bi lizes the ox - i diz ing HOF mol e cule by a hy dro gen bond. The hydroxylation bar ri ers were found to de crease with in creased co or di na tion of the ox i dized car bon atom by methyl groups, in agree ment with the ex per i ment. In the gas phase, the cal cu lated DFT/B3LYP re ac tion bar ri ers amount to 22.5, 14.5, 9.0, and 6.4 kcal/mol for ox i da tion of meth ane, eth ane, cen - tral car bon at oms of pro pane, and 2-methyl pro pane, re spec tively; for a ter mi nal C H pro - pane bond, a bar rier was enu mer ated to 13.9 kcal/mol. It was also found that the re ac tion can be cat a lyzed by the prod uct mol e cule, hy dro gen flu o ride (as first sug gested for eth yl - ene in Sertchook R., Boese A.D., Mar tin J.M.L., J. Phys. Chem. A, 110, 8275 (2006)), and com mon fea tures of the H-bond as sisted ca tal y sis were in ves ti gated. The anal o gous but very much less fa vor able hydroxylation by hypochlorous acid mol e cule was also briefly dis cussed. Key words: alkane hydroxylation, Rozen's re ac tion, hypofluorous acid, ca tal y sis

3 Pol ish J. Chem., 82, (2008) Scaled Mo lec u lar Dy nam ics Sim u la tions for Ultraintense La ser Clus ter In ter ac tions by J. Jortner ** and I. Last School of Chem is try, Tel Aviv Uni ver sity, Ramat Aviv, Tel-Aviv, Is rael ** jortner@chemsg1.tau.ac.il (Re ceived No vem ber 11th, 2007; ac cepted No vem ber 26th, 2007) New de vel op ments in the field of charge sep a ra tion in large fi nite sys tems per tain to ex - treme ion iza tion of el e men tal and mo lec u lar clus ters in ultraintense la ser fields (peak in - ten si ties Wcm 2 ) with the pro duc tion of highly charged ions (e.g., com pletely ion ized deu te rium, wa ter and meth ane clus ters or Xe 36+ ). Con cur rently and par al lel to ex - treme ion iza tion, Cou lomb ex plo sion oc curs with the pro duc tion of high-en ergy (kev MeV) ions. The large clus ter and nanodroplet sizes, for which Cou lomb ex plo sion drives ef fi cient ta ble-top dd fu sion and nucleosynthesis with heavier nu clei, pre clude the use of the tra di tional par ti cle mo lec u lar dy nam ics sim u la tion meth ods. We con sider a scal ing method for mo lec u lar dy nam ics and ex plore its va lid ity con di tions. The scal ing method will be ap pli ca ble for large fi nite sys tems (with a num ber of con stit u ents up to 10 8 and sizes up to 100 nm) where par ti cle mo tion is gov erned by long-range (e.g., Cou lomb) in ter ac tions. Key words: clus ter ex treme ion iza tion, Cou lomb ex plo sion, ta ble-top nucleosynthesis, nu mer i cal methods

4 Pol ish J. Chem., 82, (2008) On the Na ture of the In ter ac tion in Ter nary Wa ter-sul fur Di ox ide Com plexes by J. Cukras and J. Sadlej ** Fac ulty of Chem is try, Uni ver sity of War saw, Pasteura 1, War saw, Po land ** (Re ceived No vem ber 7th, 2007; ac cepted No vem ber 9th, 2007) The in ter pre ta tion of the intermolecular in ter ac tion en ergy in the ter nary 2:1 and 1:2 tri - mers has been done. The de com po si tion of the to tal in ter ac tion en ergy us ing two- and three-body sym me try-adapted per tur ba tion the ory (SAPT) pro vid ing phys i cally mean - ing ful com po nents: elec tro static, in duc tion, dis per sion and ex change terms was ap plied. Four (H 2 O) 2 SO 2 and two H 2 O (SO 2 ) 2 tri mers were an a lyzed. We com pared the con tri - bu tion of the sand wich-type pair with the con tri bu tion of the hy dro gen-bonded pairs to the to tal in ter ac tion en ergy of the trimer. The as sump tion of pairwise additivity of the in ter ac tion in the ter nary mixed tri mers is not cor rect. The three-body nonadditivity terms rep re sent as large as ca. 18% of the to tal in ter ac tion en ergy. Key words: ab inito, SAPT, nonadditivity, sul fur di ox ide-wa ter in ter ac tion

5 Pol ish J. Chem., 82, (2008) Size-de pend ent Flu o res cence Spec tra of In di vid ual Perylene Nanocrystals Stud ied by Far-Field Fluorescence Microspectroscopy Coupled with Atomic Force Microscope Observation by T. Asahi **1,3, H. Matsune ***1,3, K. Yamashita 1, H. Masuhara ****1, H. Kasai 2,3 and H. Nakanishi 2,3 1 De part ment of Ap plied Phys ics, Osaka Uni ver sity, Suita, Osaka , Ja pan 2 In sti tute of Multidisciplinary Re search for Ad vanced Ma te ri als, Tohoku Uni ver sity, Katahira, Aoba-ku, Sendai , Ja pan 3 CREST, Ja pan Sci ence and Tech nol ogy Agency, Honcho, Kawaguchi , Ja pan ** asahi@ap.eng.osaka-u.ac.jp; Tel: , Fax: ***Pre sent ad dress: De part ment of Chem i cal En gi neer ing, Kyushu Uni ver sity, Hakozaki, Higashi-ku Fukuoka , Ja pan ****Pres ent ad dress: Hamano Foun da tion, TRI-309, Minatojima-minamicho 1-5-4, Chuo-ku, Kobe , Ja pan (Re ceived No vem ber 16th, 2007; ac cepted No vem ber 23rd, 2007) Sin gle par ti cle flu o res cence spec tros copy cou pled with AFM ob ser va tion is re ported for perylene nanocrystals. Flu o res cence spec tral mea sure ment for in di vid ual nanocrystals with the size from 100 nm to 500 nm and flu o res cence ani so tropy anal y sis dem on strate that the size de pend ence in flu o res cence is in the in trin sic na ture of nanometer-sized crystal of perylene. Sin gle nanoparticle flu o res cence shows the en - hanced mono mer (M-) emis sion com pared to the bulk crys tal and a blue-shift of excimer (E-) emis sion peak wave length by de creas ing the nanoparticle size. It is found for the first time that the size de pendence is cor re lated well to the sur face-to-vol ume ra tio of nanocrystal. The size-de pend ent flu o res cence is not at trib uted to a quan tum confinement ef fect of exciton, but to a change in the elas tic prop er ties of nanocrystal with size, which in turn af fects excimer for ma tion. We dis cuss the de crease in elas tic con stant of crys tal - line lat tice due to large sur face-to-vol ume ra tio, and pro pose an em pir i cal for mula on the size-de pend ence of E-emis sion peak in the frame work of the strong cou pling model of exciton-phonon in ter ac tion. Key words: or ganic nanocrystal, perylene, sin gle par ti cle spec tros copy, flu o res cence spec tros copy, size de pend ence

6 Pol ish J. Chem., 82, (2008) Multi-Pulse Ex ci ta tion Re veals a Novel Ex cited State Path way in a Peryleneimide-Pentaphenylene Dyad by E. Fron 1, G. Schweitzer 1, J. Ja cob 2, K. Müllen 2, M. Van der Auweraer 1 ** and F.C. De Schryver 1** 1 De part ment of Chem is try, Katholieke Universiteit Leuven, and In sti tute of Nanoscale Phys ics and Chem is try (INPAC), Celestijnenlaan 200 F, 3001 Heverlee, Bel gium 2 Max-Planck-In sti tute for Poly mer Re search, Ackermannstrasse 10, Mainz, Ger many ** Mark.VanderAuweraer@chem.kuleuven.be, Frans.DeSchryver@chem.kuleuven.be (Re ceived Oc to ber 9th, 2007; ac cepted Oc to ber 23rd, 2007) The ex cited state prop er ties of a peryleneimide-pentaphenylene dyad were in ves ti gated in de tail us ing pump-probe, sin gle pho ton tim ing and three-beam pulsed ex per i ments. Upon ex ci ta tion with 395 nm pulses ultrafast en ergy trans fer was found to oc cur from the pentaphenylene to the perylene sub unit. In po lar sol vents this ex ci ta tion en ergy trans fer is fol lowed by charge trans fer from the elec tron do nor pentaphenylene to the elec tron ac - cep tor perylene. A three-beam femto second tran sient ab sorp tion tech nique re vealed the re lax ation dy nam ics of a higher ly ing sin glet state of the peryleneimide sub unit to oc cur on a pi co sec onds time scale. These re sults dem on strate the po ten tial use of the threebeam femto second tech nique in ma nip u lat ing ex cited states pro cesses. Key words: perylenemonoimide, pentaphenylene, ex cited state, ex ci ta tion trans fer, charge trans fer, femto second three-beam tran sient ab sorp tion

7 Pol ish J. Chem., 82, (2008) Carrier Dynamics and Optical Kerr Effect of Ti ta nium Di ox ide Sin gle Crys tals by Femto second Tran sient Grat ing Spec tros copy by X. Yang, L. Wang, Y. Nakato, and N. Tamai ** De part ment of Chem is try, School of Sci ence and Tech nol ogy, Kwansei Gakuin Uni ver sity, 2-1 Gakuen, Sanda , Ja pan **Fax: , (Re ceived De cem ber 18th, 2007; ac cepted De cem ber 20th, 2007) The photogenerated car rier dy nam ics and op ti cal Kerr ef fect in rutile ti ta nium di ox ide (TiO 2 ) sin gle crys tals with (100), (110), and (001) faces were ex am ined by femto second tran sient grat ing spec tros copy. The dif frac tion sig nal of the in ten sity grat ing in bare TiO 2 sin gle crys tal at 670 nm was con sid ered to be due to free elec trons or weakly trapped elec trons nearby Ti 4+ sites within the bulk. The de cay curves of tran sient grat ing were strongly de pend ent on the ex ci ta tion in ten sity but not on the types of crys tal faces. The sub se quent in ten sity-de pend ent re lax ation was in ter preted in terms of sec ond-or der elec tron-hole re com bi na tion ki net ics with the rate con stant of ~ cm 3 s 1 for both (110) and (100) faces. The op ti cal Kerr dy nam ics of bare TiO 2 ex am ined by res o nant po lar iza tion grat ing and non-res o nant in ten sity grat ing shows an ultrafast re sponse sim i lar to the sys tem re sponse func tion, in di cat ing that the Kerr sig nal is mainly due to elec tronic po lar iza tion. By the ex ci ta tion of con duc tion band elec trons of re duced TiO 2 with the ex cess en ergy of 1.7 ev, the re lax ation time con stant of hot elec trons within the con duc tion band was es ti mated to be 310 fs. In the long time re gion, the prop a ga tion of acous tic wave of 1.28 GHz was ob served, which was due to the ex cess en ergy of hot elec - tron con verted into the ther mal en ergy by elec tron-phonon scat ter ing fol lowed by the ther mal re lax ation. Key words: ti ta nium di ox ide sin gle crys tal, tran sient grat ing, elec tron-hole re com bi na - tion, op ti cal Kerr ef fect, acous tic wave

8 Pol ish J. Chem., 82, (2008) Fluorescence Studies on Benzene and Ben zene Aque ous So lu tion in Mesoporous Sil ica by T. Okada 1**, K. Yamanaka 2, Y. Goto 2 and S. Inagaki 2 1 Toy ota Phys i cal & Chem i cal Re search In sti tute, Nagakute, Aichi , Ja pan 2 Toy ota Cen tral R&D Lab o ra to ries, Inc., Nagakute, Aichi , Ja pan ** riken-okada@mosk.tytlabs.co.jp; Fax: (Re ceived No vem ber 27th, 2007; ac cepted No vem ber 30th, 2007) We have mea sured flu o res cence spec tra as well as flu o res cence de cay curves of highly or dered mesoporous sil ica, SBA-15 and FSM-16 in clud ing ben zene or ben zene aque ous so lu tion as a func tion of tem per a ture. An ef fi cient en ergy trans fer from ben zene ex cited sin glet state to a de fect in the wall of mesoporous sil ica emit ted at about 300 nm was found. On the ba sis of the de cay anal y sis, it was sug gested strongly that many of the ben - zene mol e cules ex ist in the prox im ity to the sur face of pore wall ow ing to the strong mo - lec u lar in ter ac tions be tween ben zene and sil ica wall. It is noted that the de fects in the sil ica wall seem to play an im por tant role in un der stand ing of the lu mi nes cence char ac ter - is tics of chromo phores em bed ded in mesopores. Key words: mesoporous sil ica, en ergy trans fer, de fects in sil ica wall

9 Pol ish J. Chem., 82, (2008) Ten ta tive Iden ti fi ca tion of C 3 N Radical Lu mi nes cence in Solid Kryp ton by C. Crépin 1, L. Monéron 1, S. Douin 1, S. Boyé-Péronne 1, R. Ko³os 2,3**, M. Turowski 2, M. Gronowski 2, J. Sepio³ 2, Y. Bénilan 4 and M.-C. Gazeau 4 1 Laboratoire de Photophysique Moléculaire, CNRS UPR 3361 Université Paris-Sud, Bâtiment 210, Orsay, France 2 In sti tute of Phys i cal Chem is try of the Pol ish Acad emy of Sci ences, Kasprzaka 44, War saw, Po land 3 University of Cardinal Stefan Wyszyñski, Faculty of Mathematics and Natural Sciences, Dewajtis 5, Warsaw, Poland 4 Laboratoire Interuniversitaire des Systemes Atmosphériques, Université Paris 12, Av e nue du Général de Gaulle 94010, Créteil, France ** kolos@ichf.edu.pl (Re ceived Oc to ber 16th, 2007; ac cepted No vem ber 8th, 2007) A prod uct of cyanoacetylene photodissociation in Kr ma tri ces gives rise to vis i ble emis - sion bands ten ta tively iden ti fied as due to the flu o res cence and to the phos pho res cence of the C 3 N rad i cal. This as sign ment, which in volves the low-ly ing ~ A 2 state as the fi nal one for both emis sions, is based on the iso to pic sub sti tu tion study and on for mer the o ret i - cal pre dic tions. Key words: in ter stel lar mol e cules, rare gas ma tri ces, cyanoacetylene, flu o res cence, phos pho res cence, free radical

10 Pol ish J. Chem., 82, (2008) In flu ence of Ro ta tional Vi bra tional Cou pling on Shape of Rovibrational Bands by P. Dudziec and J. Konarski ** Fac ulty of Chem is try, A. Mickiewicz Uni ver sity, Grunwaldzka 6, Poznañ, Poland ** (Re ceived Oc to ber 15th, 2007; ac cepted No vem ber 8th, 2007) The in te grated ab sorp tion co ef fi cient of rovibrational bands is cal cu lated for three dif fer - ent cases, namely for sep a rated ro ta tional and vi bra tional mo tions, for the non-rigid model which takes into ac count the cou pling be tween above men tioned mo tions us ing the Kratzer-Fues po ten tial and the soft body model, for which only rovibrational states ex ist. It is shown that the shape of P and R bands for higher ro ta tional quan tum num bers de - pends on the ap plied model of ro ta tional vi bra tional tran si tions. Key words: in ten sity, IR-tran si tions, quan tum dy nam ics

11 Pol ish J. Chem., 82, (2008) Real-Time Prob ing of Fast Photoinduced Charge-Trans fer in Elec tron Do nor-ac cep tor Model Com pounds and in Bi o log i cal Photosensors by M.M. Mar tin**, P. Plaza and P. Changenet-Barret UMR CNRS 8640 PAS TEUR, De part ment of Chem is try, Ecole Normale Supérieure, 24 rue Lhomond, Paris, France **Tel: 33-(0) , Fax :33-(0) , monique.mar tin@ens.fr (Re ceived No vem ber 26th, 2007; ac cepted No vem ber 30th, 2007) We re view some of our re sults on the role of sol vent re or ga ni za tion as an ac tual re ac tion co or di nate in a few photoinduced charge-trans fer pro cesses con cern ing: dimethylaminobenzonitrile (DMABN), bianthryl and its 10-cyano-de riv a tive and anthracenedimethylaniline (ADMA), in so lu tion at room tem per a ture. These pro cesses were stud ied by subpicosecond tran sient ab sorp tion spec tros copy. We also de scribe some of our re cent re sults on charge-trans fer pro cesses in volved in the pri mary re sponse of photoactive pro - teins such as the photoactive yel low pro tein (PYP) and the oxyblepharismin-bind ing pro - tein (OBIP). The de cid ing role of the pro tein en vi ron ment in the photophysics of the chromo phore is em pha sized. Key words: charge-trans fer, in ter nal twist ing, ultrafast spec tros copy, bi o log i cal photoreceptors

12 Pol ish J. Chem., 82, (2008) Con i cal In ter sec tions and the Elec tronic Struc ture of the Ex cited States of N-Phenyl Pyrrole a Pro to type Molecule Exhibiting Dual Fluorescence by Y. Haas 1**, S. Zilberg 1 and B. Dick 2 1 De part ment of Phys i cal Chem is try and the Farkas Cen ter for Light In duced Pro cesses, The Hebrew University of Jerusalem, Jerusalem 91904, Israel 2 Institute for Physical and Theoretical Chemistry, University of Regensburg, D Regensburg, Ger many ** yehuda@chem.ch.huji.ac.il (Re ceived Sep tem ber 23rd, 2007; ac cepted Oc to ber 17th, 2007) The mech a nism lead ing to dual flu o res cence in sub sti tuted ben zene de riv a tives is dis - cussed us ing N-phenyl pyrrole (PP) as a test mol e cule. A model based on the quasi- Jahn-Teller dis tor tion of the charge trans fer (CT) state of PP, sim i lar to that of the ben zene an ion rad i cal, is pre sented. The model helps to lo cate sta tion ary points on the S 1 sin glet ex cited state po ten tial sur face, and to con struct an en ergy level di a gram. The en ergy and struc ture of the quasi Jahn-Teller de gen er acy which is be tween S 3 and S 2 are com puted, as well as those of three con i cal in ter sec tions con nect ing S 1 and S 2. The find ings in di cate a com plex na ture of the S 1 state elec tronic state, con tain ing sev eral lo cal min ima, sta tion - ary points and sur face cross ings. The ma jor struc tural change re spon si ble for the sta bi li - za tion of the CT state is the ring quinoid de for ma tion which is a main com po nent of the en ergy dif fer ence gra di ent vec tor in the branch ing space of all S 1 /S 2 con i cal in ter sec tions. In the re sult ing charge trans fer state (which is of quinoid struc ture) the pyrrole ring can ei - ther ro tate to form a sta bi lized twisted spe cies, or re main pla nar de pend ing on sub sti tu - tion. This re sult holds also for DMABN and other mol e cules in which the do nor is a sub sti tuted amine moi ety. It is con cluded, in line with a re cent study on DMABN (Gomez et al., J. Amer. Chem. Soc., 127, 7119 (2005)) that the TICT and PICT mod els are not mu - tu ally ex clu sive, but two dif fer ent man i fes ta tions of the same phys i cal re al ity. Key words: dual flu o res cence, con i cal in ter sec tions, phenyl-pyrrole, intramolecular charge trans fer

13 Pol ish J. Chem., 82, (2008) Notes on the Flu o res cence and the Na ture of the Photocoloured Form in Photochromic Azomethines by M.I. Knyazhansky ** 7865 Blue Jay Way, Zionsville, IN 46077, USA **Last oc cu pa tion: Pro fes sor, Head of the Lab o ra tory of Photochemistry, The Re search In sti tute of Phys i cal and Or ganic Chem is try, Rostov State Uni ver sity, Rus sia ** mknyaz@ya hoo.com; Fax: (317) (Re ceived Oc to ber 8th, 2007; ac cepted No vem ber 13th, 2007) The anal y sis of the re sults ob tained by re cent in ves ti ga tions of photochromic azo - methines (anils), in clud ing the au thor s data, shows that the path way for the photo - coloured prod uct gen er a tion pro ceeds con sec u tively via (i) the S 1 ex cited state of the NH struc ture (S 1 * NHflu), aris ing from the ex cited state intramolecular pro ton trans fer OH NH and re spon si ble for the flu o res cence with the anom a lous Stokes shift (ASSflu); (ii) the ASSflu quench ing TICT struc ture (S 1 * state) with the twisted keto ring ( = 90 ) in the trans iso mer (with re spect to the C N bond, = 0 ); (iii) the un sta ble trans twisted post 1 TICT struc ture ( = 90, = 0 ) in the S 0 state, which is the im me di ate pre cur sor of (iv) low-sta bil ity post 2 TICT cis struc ture twisted in the S 0 state ( = 90, 180 ). The lat ter is re spon si ble for the photo chrom ism of anils and sta bi lized by steric in ter ac - tions and rigid me dia. Key words: anils, photo chrom ism, TICT, post TICT

14 Pol ish J. Chem., 82, (2008) En hance ment of Photoacidity by For ma tion of an Intramolecular Charge Trans fer State with Twisted Con for ma tion by B. Szczepanik 1**, R. Obara 1, A. Rothe 2, W. Weigel 2, W. Rettig 2***, M. Stachera 1 and K. Rotkiewicz 1,3 1 In sti tute of Chem is try, Œwiêtokrzyska Acad emy, Chêciñska 5, Kielce, Po land ** Beata.Szczepanik@pu.kielce.pl 2 Institut für Chemie, Humboldt-Universtät zu Berlin, Brook-Tay lor-str. 2, D Berlin, Ger many ***Fax: (+49 30) , rettig@chemie.hu-berlin.de 3 In sti tute of Phys i cal Chem is try, Pol ish Acad emy of Sci ence, Kasprzaka 44, Warsaw, Poland (Re ceived No vem ber 6th, 2007; ac cepted De cem ber 27th, 2007) The syn the sis of a pair of bi phen yls with a cyano ac cep tor and a hydroxy (methoxy) do - nor, which dif fer in the ex tent of steric hin drance to pla nar ity, in duced by ortho-methyl sub stitu ents with re spect to the phenyl phenyl bond is de scribed. It is shown that dual flu o res cence can be ob served, as cribed to a mesomerically sta bi lized less po lar intra - molecular charge trans fer (MICT) state of near pla nar ge om e try, and a more po lar one, with strongly de coup led intramolecular CT re sem bling a TICT state. It pos sesses an en - hanced di pole mo ment with re spect to the MICT state, but con sid er ably de vi ates from the per pen dic u lar ge om e try as judged from the tran si tion mo ments. This con cept is used in con junc tion with the ex cited-state pro ton trans fer (ESPT) mech a nism. The re sult ing photoacidity of the com pound form ing the en hanced ICT is an or der of mag ni tude larger than for the MICT-com pound. The mech a nis tic con cept al lows the con struc tion of fur ther com pounds with still in creased photoacidity. Key words: intramolecular charge trans fer ex cited states, superphotoacidity, 4-cyano - phenol, 4-hydroxy-4 -cyanobiphenyls, time re solved flu o res cence \

15 Pol ish J. Chem., 82, (2008) The Ex cited State Re lax ation Path of N,N-Di ethyl-5-cyanopyridine and N,N-Diethylbenzaldehyde by J. Dobkowski ** and I. Sazanovich a In sti tute of Phys i cal Chem is try, Pol ish Acad emy of Sci ences, Kasprzaka 44, War saw, Poland ** dobkowsk@ichf.edu.pl a Per ma nent ad dress: B.I. Stepanov In sti tute of Phys ics, National Acad emy of Sci ences of Belarus, Prosp. Nezavisimosti 68, Minsk , Belarus (Re ceived No vem ber 12th, 2007; ac cepted No vem ber 19th, 2007) The mol e cules which pos sess, as elec tron do nors, dialkylamino groups linked by a sin gle bond with the ac cep tor sub units un dergo fast ex cited state intramolecular charge trans fer (ICT), emit ting dual flu o res cence in po lar sol vents. The short and the long-wave length flu o res cence bands are tra di tion ally as signed as F b and F a, re spec tively. The na ture of the ex cited state from which the F a emis sion orig i nates, as well as the mech a nism of en - ergy deg ra da tion have been the sub ject of many con tro ver sies. As the ob jects of this study, 2-(N,N-di ethyl)-5-cyanopyridine (PEC) and p-n,n-diethylaminoacetophenone (DEABA) were se lected. For these mol e cules dif fer ent se quence of the two low-ly ing * L a and L b states was pos tu lated, which can help to ver ify the ex cited state mech a - nisms of the charge sep a ra tion. The ex per i men tal re sults ob tained by sta tion ary and time-re solved spec tros copy show that the anom a lous F a emis sion orig i nates from the ICT state gen er ated by the mu tual twist of the do nor and ac cep tor group (TICT model). Key words: elec tron trans fer, TICT state, time-re solved spec tros copy

16 Pol ish J. Chem., 82, (2008) Hy dro gen Bond ing and Protonation Ef fects on Ex cited-state Elec tron Trans fer in metaand para-dialkylaminopyridines by I. Szyd³owska 1, J. Nowacki 2, A. Zieliñska 1 and J. Herbich 1,3** 1 In sti tute of Phys i cal Chem is try, Pol ish Acad emy of Sci ences, Kasprzaka 44/52, War saw, Po land 2 De part ment of Chem is try, War saw Uni ver sity, Pasteura 1, War saw, Po land 3 Fac ulty of Math e mat ics and Natural Sci ences, Car di nal Stefan Wyszyñski Uni ver sity, Dewajtis 5, War saw, Po land ** herbich@ichf.edu.pl (Re ceived No vem ber 29th, 2007; ac cepted De cem ber 14th, 2007) Syn thetic, spec tral and photophysical in ves ti ga tions were per formed for a se ries of dialkylaminopyridines (DAAPs) rep re sent ing elec tron do nor-ac cep tor sys tems. 4-Dimethyl aminopyridine and its an a logues, sub sti tuted by an elec tron do nor at the para po si tion of the ac cep tor ring, show sol vent-de pend ent dual lu mi nes cence from the sub - strate (pri mary ex cited state) and the prod uct (TICT state) of the photoinduced elec tron trans fer pro cess. The in ves ti ga tions in mixed sol vents (n-hex ane + 1-butanol) al low us to prove that dual lu mi nes cence is ob served for 1:1 com plexes of 4-DAAPs with the al co hol mol e cule hy dro gen-bonded to the pyridine ni tro gen atom. Con trary to 4-DAAPs, the elec tronic struc ture and ge om e try of the flu o res cent CT state of 3-diisopropyl amino - pyridine are sol vent-de pend ent (this 1 CT state does not cor re spond to a full sep a ra tion of charges). The spec tro scopic and photophysical prop er ties of the protonated forms of DAAPs are also pre sented. It is note wor thy that the monocations of 4-diiso propyl - aminopyridine ex hibit TICT flu o res cence. Key words: dialkylaminopyridines, photoinduced intramolecular elec tron trans fer, dual flu o res cence, TICT state, hy dro gen bond ing and protonation ef fects

17 Pol ish J. Chem., 82, (2008) Photoinduced Intramolecular Charge Sep a ra tion and Re com bi na tion in a Do nor-ac cep tor Dyad Linked via Tet ra he dral Car bon Atom. Photophysics of a Mal a chite Green Lactone An a logue by J. Karpiuk 1,**, E. Karolak 1 and J. Nowacki 2 1 In sti tute of Phys i cal Chem is try, Pol ish Acad emy of Sci ences, Kasprzaka 44/52, War saw, Po land 2 De part ment of Chem is try, War saw Uni ver sity, Pasteura 1, Warsaw, Poland ** karpiuk@ichf.edu.pl, fax: (Re ceived De cem ber 19th, 2007; ac cepted De cem ber 20th, 2007) Lactone forms of triarylmethane dyes (LTAM) with do nor-ac cep tor-do nor triad struc ture un dergo ultrafast quan ti ta tive intramolecular charge sep a ra tion (CS) with for ma tion of a highly po lar 1 CT state. To clar ify the role of the elec tron do nat ing part in the CS pro cess, 3-methyl-3-(4-dimethylaminophenyl)phthalide (MGLA), an an a logue of malachite green lactone (MGL) with only one D part in a D A dyad struc ture has been syn the sized and its photophysics com pared to those of MGL, leucomalachite green (MGH) and mal a chite green leuconitrile (MGCN). The photoinduced elec tron trans fer pro cesses in MGLA show close anal ogy with MGL and prove that (i) the tet ra he dral car bon atom cou pled with C O bond in quasi-spiro con fig u ra tion is a very ef fi cient link in ultrafast intramolecular elec tronic com mu ni ca tion and that (ii) the photoinduced charge sep a - ra tion and re com bi na tion pro cesses in LTAM mol e cules in volve es sen tially only one elec tron-do nat ing group. Key words: mal a chite green lactone, 3-methyl-3-(4-dimethylaminophenyl)phthalide, triaryl methane lac tones, ultrafast intramolecular elec tron trans fer, solvatochromism of ab sor p tion and flu o res cence bands

18 Pol ish J. Chem., 82, (2008) Ev i dence for Heterolytic Cleav age of C S Bonds in the Photolysis of 1,3,5-Trithianes by G.L. Hug 1,2, E. Janeba-Bartoszewicz 1, P. Filipiak 1, T. Pedzinski 1, H. Kozubek 1 and B. Marciniak 1*** 1 Fac ulty of Chem is try, Adam Mickiewicz Uni ver sity, Grunwaldzka 6, Poznan, Po land 2 Ra di a tion Lab o ra tory, Uni ver sity of No tre Dame, No tre Dame, IN 46556, USA ***phone: ; fax: ; marcinia@amu.edu.pl (Re ceived Oc to ber 22nd, 2007; ac cepted No vem ber 6th, 2007) The homolytic/heterolytic na ture of photolytic C S bond cleav age was stud ied in 1,3,5-trithianes. The mech a nism of photolysis was re fined from pre vi ous stud ies. First, ev i dence was pre sented for the ex is tence of a pre cur sor of the biradical-like tran sient (I) which it self was iden ti fied in pre vi ous stud ies. Sec ond, the na ture of I was fur ther clar i - fied through meth a nol-scav eng ing ex per i ments where the re sults could be in ter preted as lend ing cred i bil ity to the no tion that I has sig nif i cant bi po lar char ac ter. Ki netic and spec - tral anal y ses of tran sient ab sorp tions, fol low ing la ser ex ci ta tion of the trithianes, showed that I was re act ing with meth a nol. Com ple men tary steady-state photolytic quan tum yields sup ported this find ing, and ad di tional, but un iden ti fied, sta ble prod ucts from ir ra - di a tions in meth a nol were seen in the HPLC. The for ma tion of these prod ucts was in ter - preted as likely aris ing from a nucleophilic at tack of meth a nol at the carbocationic end of the bi po lar struc ture of I. Key words: trithianes, C S bond cleav age, photolysis

19 Pol ish J. Chem., 82, (2008) Ex cited-state Sol va tion of Rhodamines: Di elec tric and Spe cific Con tri bu tions by J.A.B. Ferreira ** and S.M.B. Costa Centro de Química Estrutural, Complexo Interdisciplinar, Instituto Su pe rior Técnico, Av. Rovisco Pais, Lisboa, Por tu gal ** or Phone: ; Fax: /7 (Re ceived No vem ber 12th, 2007; ac cepted No vem ber 16th, 2007) Pri mary to ter tiary amine based com pounds of the form 9 -(2-es ter-car bonyl)-phenyl- 3,6 -bis-(amino)-xanthylium) are stud ied as mod els for this class of com pounds as re - gards the S 1 S 0 shifts in so lu tion. The mag ni tude of the solvatochromic shift de - creases from pri mary amine to ter tiary amine rhodamine chromo phore. Pri mary amino xanthylium spec tral en ergy at max i mum ab sorp tion de creases with the sol vent elec tronic po lar iza tion whilst it in creases with the orientational po lar iza tion func tion, sug gest ing ex ten sive re ori en ta tion in the dipolar mo ment upon S 1 S 0 ex ci ta tion. By con trast, upon elec tronic ex ci ta tion smaller dipolar mo ment vari a tions are found in N-alkyl rhodamines, re spec tively with sec ond ary and ter tiary amine groups. Pri mary and sec ond ary amine rhodamines NH groups es tab lish strong in ter ac tions with elec tron rich atomic cen ters of sol vent mol e cules in creas ing the elec tronic sta bi li za tion en ergy. Key words: rhodamine, solvato chromism, re ac tion field, hy dro gen bond ing

20 Pol ish J. Chem., 82, (2008) In for ma tion Con tent in Lin ear Dichroism Spec tra by P.W. Thulstrup 1** and E.W. Thulstrup 2*** 1 De part ment of Nat u ral Sci ences, Fac ulty of Life Sci ences, Uni ver sity of Co pen ha gen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Den mark 2 De part ment of Sci ence, Sys tems and Mod els, Roskilde Uni ver sity, POB 260, DK-4000 Roskilde, Den mark ** pwt@life.ku.dk; ***ewt@ruc.dk (Re ceived No vem ber 20th, 2007; ac cepted No vem ber 23rd, 2007) Spec tros copy with lin early po lar ized light on aligned sam ples (LD spec tros copy) is a use ful tech nique that may greatly en hance the pos si bil i ties for de ter min ing sam ple struc - ture, mak ing spec tral as sign ments, and sev eral other tasks, gen er ally based on a de ter mi - na tion of tran si tion mo ment di rec tions. How ever, the tech nique does not pro vide the same amount of in for ma tion in all cases; this de pends strongly on the mo lec u lar sym me - try. The al most ideal case is that of D 2h, D 2, or C 2v sym me try, when only 3 dif fer ent (per - pen dic u lar) tran si tion mo ment di rec tions are pos si ble. When the mo lec u lar sym me try de creases, the in for ma tion that may be ob tained be comes less pre cise. If the mol e cule has a plane of sym me try left, the tran si tion mo ment may be lo cated per pen dic u lar to the sym me try plane or at any di rec tion in the plane, and much use ful in for ma tion may still be ex tracted. In the case of a mol e cule with no sym me try at all the in for ma tion that can be ob tained of ten be comes highly qual i ta tive, un less spe cial in for ma tion hap pens to be avail able. Un for tu - nately, this se vere lim i ta tion is some times over looked when low-sym me try mol e cules are stud ied, and the spec tra are eval u ated the same way spec tra for sym met ri cal mol e cules are. This is an ob vi ous source of er ror, and con clu sions based on such an anal y sis are hardly re li able. In this pa per, the spec tro scopic tech nique, as sump tions com monly made, and the math e - mat i cal treat ment of IR and UV spec tra are briefly sum ma rized for dif fer ent mo lec u lar sym me tries. This is il lus trated by a few ex am ples, in clud ing new IR LD spec tra of limonene, a very dif fi cult, low sym me try case. Key words: po lar iza tion, UV-VIS, IR, LD spec tros copy

21 Pol ish J. Chem., 82, (2008) The Vi bra tional Struc ture of Dibenzo-p-di oxin. IR Lin ear Dichroism, Raman Spec tros copy, and Quan tum Chem i cal Cal cu la tions by T.K. Eriksen, B.K.V. Hansen and J. Spanget-Larsen ** De part ment of Sci ence, Sys tems and Mod els, Roskilde Uni ver sity, P. O. Box 260, DK-4000 Roskilde, Den mark **Tel.: ; spanget@ruc.dk (J. Spanget-Larsen) (Re ceived June 28th, 2007; ac cepted Sep tem ber 14th, 2007) The ti tle com pound (DD) was in ves ti gated by IR and Raman spec tros copy, in clud ing FTIR lin ear dichroism (LD) mea sure ments on sam ples aligned in stretched poly eth yl ene. The ob served IR and Raman wavenumbers, IR po lar iza tion di rec tions, and rel a tive in ten - si ties were gen er ally well re pro duced by the re sults of a har monic anal y sis based on B3LYP/cc-pVTZ den sity func tional the ory (DFT). The com bined ex per i men tal and the - o ret i cal re sults led to pro posal of a nearly com plete as sign ment of the fun da men tal vi bra - tional tran si tions of DD, in volv ing re as sign ment of sev eral tran si tions. The re sults are con sis tent with the as sump tion of mo lec u lar D 2h sym me try, thereby sup port ing the con - clu sion reached ear lier by Gastilovich and co work ers. Key words: di ox ins, vi bra tional tran si tions, in fra red spec tros copy, Raman spec tros copy, lin ear dichroism, po lar iza tion di rec tions, den sity functional theory

22 Pol ish J. Chem., 82, (2008) Cor re la tions of Charges of Substituent Ac tive Re gion in C-sub sti tuted Tetrazoles with Their Gas-phase Acid ity, Hammett Con stants, and Charge Dis tri bu tion in Tetrazolic Rings by N. Sadlej-Sosnowska ** and K. Mur³owska Na tional Med i cines In sti tute, 30/34 Che³mska Street, War saw, Po land ** sadlej@il.waw.pl (Re ceived Oc to ber 19th, 2007; ac cepted No vem ber 6th, 2007) Elec tron dis tri bu tion was in ves ti gated in mol e cules of 5C-sub sti tuted tetrazoles by means of Nat u ral Pop u la tion Anal y sis. The anal y sis of the im pact of sub stitu ents on the ex cess of elec trons in the ring and on the uni for mity of their dis tri bu tion pro duced sim i - lar re sults as were re cently re ported for de riv a tives of p-ben zoic acid. The sig nif i cant cor - re la tion co ef fi cients of the two prop er ties with the Hammett con stants have been found. The more uni form the elec tron dis tri bu tion, mea sured by means of stan dard de vi a tion of elec trons amounts lo cal ized on in di vid ual at oms in the ring, the more acidic is the mol e cule. On the other hand, an in crease of the elec tron num ber in the ring brings about an op po site ef fect. No cor re la tion was found be tween the substituent charges and the Hammett con stants. How ever, a new vari able, namely charge of the substituent ac tive re - gion, com posed of charge of a substituent added to charge of the ring C ipso atom, was highly cor re lated with the Hammett con stants, as well as with charge of acidic hy dro gen of the >N H group. The re sults prove that the set of charges of the substituent ac tive re - gion may be per ceived as a the o ret i cal equiv a lent of the ex per i men tal set of Hammett con stants and that it is closely re lated to prop er ties of this group of com pounds. Key words: tetrazoles, sub stitu ents, Hammett con stants, gas-phase acid ity, charge dis - tri bu tion, Nat u ral Pop u la tion Anal y sis, substituent ac tive region

23 Pol ish J. Chem., 82, (2008) Pro ton or Hydrogen Transfer? Charge Dis tri bu tion Anal y sis by J. Waluk** Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44, War saw, Po land ** waluk@ichf.edu.pl (Re ceived No vem ber 9th, 2007; ac cepted No vem ber 16th, 2007) The mean ing of terms pro ton trans fer (PT) and hy dro gen trans fer (HT), com monly en coun tered in the lit er a ture, is not al ways un am big u ous, es pe cially in the case of intramolecular tautomerization pro cesses. De pend ing on the used cri te rion, the same re - ac tion may be clas si fied as ei ther PT or HT. Two cri te ria for dis tin guish ing be tween PT and HT are dis cussed: (a) for mal translocation of charge; (b) the re ac tion mech a nism, in par tic u lar the cou pling be tween the mo tion of the pro ton and the elec tron den sity re dis tri - bu tion. The anal y sis is il lus trated us ing the val ues of ground and ex cited state par tial charges cal cu lated for three well-known ex am ples of mol e cules that un dergo photo - induced and/or ground state tautomerization: 2-hydroxyacetophenone, 2,2 -bi pyridyl- 3,3 -diol, and porphycene. Key words: pro ton trans fer, hy dro gen trans fer, charge dis tri bu tion