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The development of chromophores that absorb in the near-infrared (NIR) region beyond 1000 nm underpins numerous applications in medical and energy sciences, yet also presents substantial challenges to molecular design and chemical synthesis. Here, the core bacteriochlorin chromophore of nature's NIR absorbers, bacteriochlorophylls, has been adapted and tailored by annulation in an effort to achieve absorption in the NIR-II region. The resulting bacteriochlorin, Phen2,1-BC, contains two annulated naphthalene groups spanning meso,β-positions of the bacteriochlorin and the 1,2-positions of the naphthalene. Phen2,1-BC was prepared via a new synthetic route. Phen2,1-BC is an isomer of previously examined Phen-BC, which differs only in attachment via the 1,8-positions of the naphthalene. Despite identical π-systems, the two bacteriochlorins have distinct spectroscopic and photophysical features. Phen-BC has long-wavelength absorption maximum (912 nm), oscillator strength (1.0), and S1 excited-state lifetime (150 ps) much different than Phen2,1-BC (1292 nm, 0.23, and 0.4 ps, respectively). These two molecules and an analogue with intermediate characteristics bearing annulated phenyl rings have unexpected properties relative to those of non-annulated counterparts. Understanding the distinctions requires extending concepts beyond the four-orbital-model description of tetrapyrrole spectroscopic features. In particular, a reduction in symmetry resulting from annulation results in electronic mixing of x- and y-polarized transitions/states, as well as vibronic coupling that together reduce oscillator strength of the long-wavelength absorption manifold and shorten the S1 excited-state lifetime. Collectively, the results suggest a heuristic for the molecular design of tetrapyrrole chromophores for deep penetration into the relatively unutilized NIR-II region. [ABSTRACT FROM AUTHOR]

An automated phosphoramidite method is used to synthesize and incorporate into locked nucleic acid (LNA) oligonucleotides the second generation 2'-O,4'-C-methylene-linked nucleotides. These contain hypoxanthine, 2,6-diaminopurine and 2-aminopurine nucleobases that have unique properties to further strengthen LNA technology.

Porphyrin building blocks bearing 1-4 swallowtail groups were obtained by studying synthetic routes. The swallowtail substituents do not alter the electronic or photophysical properties of the porphyrins, making them apt as building blocks for constructing large arrays for detailed physicochemical studies.

A set of hydroporphyrins, which consists of chlorin-chlorin and oxochlorin-oxochlorin are prepared with components in the same or different metalation states and studied using static and time-resolved absorption and emission spectroscopy, resonance Raman spectroscopy and electrochemical techniques. Further, a comparison between the excited-state energy transfer in arrays of hydroporphyrins and porphyrins is conducted.

A new perylene-oxochlorin dyad is synthesized and characterized for potential use in light-harvesting applications. The findings are consistent with the expectation that all charge-separated states such as perylene-monoimide (PMI)(super -1) ZnO(super +) lie energetically above both PMI and ZnO in both polar and nonpolar media.

In this study, a perylene-bis(imide)-oxochlorin dyad is synthesized to identify charge-injection or molecular-switching motifs for use in molecular photonics. Each dyad is studied in both polar and nonpolar media using static and time-resolved optical spectroscopy and electrochemical techniques.

Research has been conducted on the C-alkylated zinc chlorins. The two-step conversion of these compounds to zinc oxochlorins with the keto group located in the macrocycle's reduced ring has been carried out and the details are described.

Attempts made to investigate the self-motion of a camphor grain on a linear water route are presented. The essential features of the self-motion were reproduced by numerical calculations in relation to the spatial distribution of the camphor layer at the air-water interface.

Efforts made to study the mechanism of gating in linear versus branched multiporphyrin arrays, static and time-resolved optical spectroscopy is used. The results show the photophysics of gating and afford great flexibility and control in the design of more elaborate arrays for molecular photonics applications.

The cationic states of the lanthanide porphyrin-phthalocyanine triple-decker sandwich molecules are exceptionally attractive for molecular information storage applications. Triple-decker building blocks bearing ethyne, iodo, or iodo and ethyne groups can be prepared in a straightforward manner.

A study concerning the synthesis of porphyrins covalently linked to a phthalocyanine is presented. The cyclotetramerization of an ethyne-linked porphyrine-phthalonitrile in 1-pentanol is described.

The very low-frequency modes of the dimer of bacteriochlorophylls (BChl) which are strongly coupled to the P electronic transition initiating primary charge separation process in bacterial photosynthetic reaction centers (RC) are identified. The low-frequency, near-infrared-excitation resonance Raman spectra of RCs from Rhodobacter sphaeroides, where BChl and bacteriopheophytin cofactors are labeled with 15N or 26Mg, are analyzed, Results indicate that the strongly coupled modes involve motions limited on pyrrole ring I and the macrocycle core.

The application of the different thallium hyperfine clocks in determining the rate of hole transfer exhibited by the oxidized porphyrin dyads is discussed.

The hyperfine-clock strategy is applied to dyads of dihydroporphyrins (chlorins) and a de novo synthetic strategy is used to introduce a [super 13]C label at the 19-position of the chlorin macrocycle. The analysis of the chlorin and phorphyrin dyads has provided insights into the structural features that affect the hole/electron-transfer process.

A new rational route is developed for preparing 8,9-dibromou1-formyldipyrromethane that lead to In[Cl.sub.3]-catalyzed condensation of 4-bromo-2-(hydroxymethyl)pyrrole and prrole to give the 8-bromodipyrromethane, 1-formylation and 9-bromination. The photophysical and redox properties of the 13-substituted chlorines are compared with those of isomeric 12-substituted chlorines, which are prepared via a 7,9-dibromo-1-formyldipyrromethane.

The ground-state hole-transfer processes are studied in a series of oxidized porphyrin triads (ZnZnFb) in order to determine the rates between the nominally equivalent sites (Zn/Zn). The rate constants obtained from the analysis have helped in the design of molecular constructs for a variety of solar-energy applications.

A p-diphenylethyne-linked zinc porphyrin dyad with two [super 13]C atoms and one unlabeled was prepared to understand ground-state hole/electron-transfer process in oxidized multiporphyrin architectures. The slower hole-transfer rate compared to that of meso-diphenylethyne-linked, electron-rich porphyrin dyads is attributed to the [a.sub.2u] HOMO with substantial electron/spin density at the meso-carbons.

The investigation of the ground-state electronic communication in diphenylethyne-linked zinc-porphyrin dyads was observed to be fast on the time scale of the [super 13]C hyperfine clock.

A set of porphyrin-porphyrin and oxochlorin-oxochlorin dyads are prepared in which the constituent pigments are joined at the meso-proteins by the phenylethyne linker. The results shown and observed are useful in the design of multi pigment architectures that absorb in the red and undergo fast and efficient energy transfer, as required for light-harvesting applications.

Research has been conducted on zinc porphyrins connected via intervening bis(dipyrrinato)metal complex. The authors describe the synthesis and characterization of triads composed of zinc porphyrins' linear array.

Research has been conducted on multiporphyrin arrays. The authors describe the synthesis of these arrays carried out via the prepared and characterized dyads composed of both zinc and free-base porphyrins connected by imine-based linker.