Helmut Jahn is a state-of-the-art architect in a cutting-edge city. If nothing else, the architect has swelled the number of adjectives used in discussing Chicago design.
A whole roster of words have entered the lexicon of the city's core to describe his latest concoctions. The German-born designer has pulled out the full repertoire of architectural stops. Swirls, slopes, swerves, scallops - not to mention undulations, truncations, and stops and starts of all the above - characterize his structures.
For much of a decade, Jahn has gone to all lengths to avoid the right-angled box, from the low, round, checkerboard Argonne National Laboratory to the erratic, jutting red and blue missile planned for a South African commercial building.
Within the dark masonry canyons of the Windy City, especially, his latest four buildings of the '80s have zapped the down-to-earth image of the 80 -architect firm of C.F. Murphy (now Murphy/Jahn) with the electricity of their lightning-rod looks.
''Dear Mies,'' a fellow architect addressed the bygone father figure of the international style in the magazine Architectual Record a few years ago. ''When you were here, the C.F. Murphy firm was solid. . . . Now this fellow Helmut Jahn is doing some strange things.''
Strange? ''Rational and intuitive,'' Jahn responds.
Sitting in his office recently, his gray silk hat and jacket draped over a chrome chair, the prince of panache answers questions in a calm, pragmatic fashion. ''Buildings also have to be reasonable in adhering to certain principles,'' he says. ''Mies was as drastically different as any architect in any time. With 20 or 30 years distance, we feel his architecture fits.''
Jahn is not alone here in swerving from the stone-and-steel tradition of the city this decade. Kohn Pedersen's recent deco design at 333 Wacker Street; the dog face contoured into the veterinarian hospital by Stanley Tigerman; and the pyramid-fronted building now rising on the Magnificent Mile display the forms that make the history of Chicago's architecture one of architectural innovation.
But even within this inventive tradition, Jahn's unsettling quartet in the city core - One South Wacker Drive, the addition to Holabird and Root's Board of Trade Building, the Xerox Centre, and his almost-finished Illinois state office building - puts him at center stage.
''Infill'' is the firm's description of the striking glass Xerox Centre with its rounded corner, ''infill'' meaning that the building has a nice fit in the context of the street. Nonetheless, in the range between context and conspicuousness, one would have to describe most Jahn buildings as less than deferential to the context of the city. The glistening facade and strange form of the latest showstopper State of Illinois Building, above all, is hardly a token nod to one's notion of downtown.
No two sides of the $170 million, 100-million-square-foot structure are alike. From top (250 feet) to bottom, the building changes form and color. Its shape (180 feet in diameter) is polygonal; its roof, sliced; its sides, three tones of blue glass, darkening as they touch the ground.
For all the oddities of the shape, the firm insists the monument merits the phrase a ''people's building'' for its inside atrium. Certainly the model is a striking one. Somehow, though, the structure appealed more in visual projections than on the street, where it is awkward in its relations and not so elegant in materials.
Strangely, this seems the case for many Murphy/Jahn buildings.
A walk through the firm's recently renovated quarters is indeed a walk through a delightful Jahn museum: Sheafs of sketches of buildings limned with an energy, fluidity, and an impressive imagination show his formal and technical skill.
On the street here, however, the imagination's whirls look more unsettled, and the resulting architecture receives more mixed reviews. For all the individualistic formmaking, the signature materials in the company's gee-whiz buildings sometimes have a cold, slick air.
The period under scrutiny in Jahn's skyscrapers is the '20s and '30s, and the nostalgia-cum-high-tech version of his high style can enliven interiors. One South Wacker Drive, again especially in photographs, has a dramatic flair. The details in the addition to the Board of Trade Building have a finesse and show a caring hand in matching the past.
Often, however, the sleek mix of the streamlined and the modernized is less a romantic delight than an evocation of a period we can admire but not always emulate: One South Wacker seems a hollow chamber awaiting the dash of Fred Astaire. So, too, Jahn's 12-story glass-covered atrium in the Board of Trade's 12-story galleria produces a somewhat surreal space.
At the same time, the architect can deploy architecture's eternal life-enhancing element - light - with elegance: The Xerox Centre is luminous; light dances down from diagonal ceiling lights, bounces from the glass entrance, reflects surfaces with splash and elegance.
Elsewhere, Jahn contributes color to the vocabulary of architecure. His blue police station near Pullman is both a symbol and a lively facade. Even the glacial whites of the Xerox Centre or the grays and blacks of One South Wacker create tones within their monochromes.
Jahn's treatment of his company's offices steps back from the self-conscious streamlining recalled in the forthcoming Northwestern Terminal or the slash-dazzle acrobatics of the tapering Bank of Texas tower drawing. He has inserted an attractive mix of deco and high-tech in the old quarters. The gray floor, banded with red; the gridded screening; even the trusses of the industrialized balustrades on the stairs sum Jahn themes in an apt fashion, refraining from pushing architecture beyond its limitations.
Jahn enjoys pushing these limits. He likes the stretch for new technology; he has the visual creativity for new forms and sees himself as reaching out for a ''futurist'' architecture in a country which has lost faith in that future.
That is the fascination of an architecture that has expanded the language of design. It is also the danger in buildings that have yet to adopt another vocabulary - one with words like intimacy, warmth, and urban vivacity. Unfortunately, only when that full range of adjectives enters the discourse of design can a position on the cutting edge of architecture create a future city that appeals to the full range of humanity that inhabits it.