Serialized holography for brand protection and authentication.

The problems presented by counterfeit products and documentation are discussed. Limitations of existing holograms for anti-counterfeit applications are described. We describe the advantages of full holographic serialization and the requirements in terms of materials and techniques for mass production of true serialized holograms.

Structural investigation of 5,10-A2B2-type porphyrins: palladium(II) and zinc(II) complexes of 5,10-dibromo-15,20-bis(4-methylphenyl)porphyrin.

The analysis of [5,10-dibromo-15,20-bis(4-methylphenyl)porphyrinato]palladium(II), [Pd(C34H22Br2N4)], and [5,10-dibromo-15,20-bis(4-methylphenyl)porphyrinato](methanol)zinc(II), [Zn(C34H22Br2N4)(CH4O)], reveals a small but localized influence of the bromine residues on the conformation of the macrocycle. A comparison of the 5,10-dibromo substituent pattern with literature data for 5,15-dibromoporphyrins shows similar in-plane distortions in both but a different mix of out-of-plane distortion modes for the different regiochemical arrangements.

Solvent effect on the nonlinear absorption of 5,10-A(2)B(2) meso substituted porphyrins.

The effect of the solvent on the nonlinear absorptive properties of two series of 5,10-A2B2 porphyrins was investigated with an open Z-scan technique in the ns time regime. The recorded responses, which varied between compounds and solvents, were fitted to a four-level model where the one-photon excited state absorption is followed by a two-photon process arising from the higher excited states. For most of the compounds the positive nonlinear absorption in toluene was stronger than that in DMF and chloroform.

Nonlinear absorption properties of 5,10-A2B2 porphyrins--correlation of molecular structure with the nonlinear responses.

The nonlinear absorption properties of two series of novel free base and metalated meso 5,10-A2B2 substituted porphyrins, both bearing p-tolyl as an A substituent and TMS-ethynyl or bromine as a B substituent, were investigated with the open Z-scan technique at 532 nm in the ns time regime. Most of the compounds exhibited a transmission drop with increasing input fluence. This behavior is desirable for their applications in optical limiting.

Modeling of nonlinear absorption of 5,10-A2B2 porphyrins in the nanosecond regime.

The nonlinear absorption (NLA) properties of free base and metalated porphyrins with a unique 5,10-A(2)B(2) substitution pattern were studied with open Z-scan technique at 532 nm in the nanosecond regime over a broad range of input fluence. The NLA responses were found to be dependent on structural features and the solvent used. In most cases, the character of the response differed from that typically observed for other porphyrins under similar experimental conditions (i.

5,10-A2B2-type meso-substituted porphyrins--a unique class of porphyrins with a realigned dipole moment.

Current applications in porphyrin chemistry require the use of unsymmetrically substituted porphyrins. Many current industrial interests in optics and biomedicine require systems with either push-pull (electron-donating and -withdrawing groups) or amphiphilic systems (hydrophobic and hydrophilic groups). In this context we present the class of 5,10-A(2)B(2)-type porphyrins for which two different substituents are positioned in diagonally opposite meso positions.